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DISCLAIMER

This article explains how to protect wood from pests, water and fire showing different environmental-friendly techniques

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DE BLOWA

UseProtectionLimitationInterior & exterior wood,
termites-infested woodKilling and repelling termites and other pestsIf a change in colour is not appriciated

DE BLOWA is a mixture of proven anti-termite and anti-pest ingredients that we at Critical Concrete used to protect almost all of the wood we use. So far, we haven’t done any long-term research into its effectiveness, but we’re optimistic that it’s a very useful combination because all of the ingredients are individually useful treatments for pests. The name is an abbreviation for the materials it contains:

DEDiatomaceous Earth100 gB
Borax100 gLLinseed Oil3 kgOOrange Oil100 gWAWood Ashes100 g

It is important to shake the mixture well before application, as the ingredients are not dissolving and settling on the bottom of the container. Then the mixture can be easily applied with a brush (or for a larger surface with a paint roller). Users should be aware that DE BLOWA gives the wood a darker shine. If a fine result is required, the excess should be removed a few minutes after brushing with a cloth.

ProTip: If the wood is already infested, it is recommended to briefly pull the wood through fire from all sides to kill the termites. Another option is to inject orange oil into the visible termite tunnels with a syringe. Read more about the single ingredients and techniques in the following article!

Interested in using this technology in your project?

Critical Studio can help!

Learn More!

Introduction

Wood is a versatile and renewable material with a positive carbon footprint, which proves to be a significant construction material in sustainable architecture. Because of its strong and lightweight characteristics and the possibility to be processed and worked easily, it is a good replacement for other, less ecological materials. Additionally, wood is a relatively cheap material and gives any construction a cozy and natural atmosphere.

All these advantages make wood one of our most used materials within our projects. For example, instead of concrete or metal, the heavy load of our green roof is carried by strong wooden laminated beams of 12x48cm. Also, reclaimed wooden windows are giving a unique touch to the backyard facade of our workshop.

Beams carrying the green roof

The facade in process

Despite the mentioned advantages, wood as a building material still faces some persistent prejudices, which can lead people to refrain from using wood in their constructions. Many bacteria, fungi and insects find wood appetizing, and humidity and moisture can lead to its early decay. Besides this, a misconception associates wood with being very flammable and thus, a risky building material (when in fact wood retains its strength longer and at much higher temperatures than steel [1]). So, if wood is prepared and treated in an appropriate way, it can be turned into a long-lasting, water- and bacteria-proof as well as fire resistant building material. Many still-standing examples prove that wooden structures can last over centuries and, taking their time of origin into account, that wood can be protected without any artificial products.

House on the Faroe Islands

When it comes to protecting wood from the mentioned dangers, one can already find a lot of articles on the internet. In this article we avoid the commonly used methods which often involve ingredients harmful to the environment and instead focus on the natural and non-toxic techniques. Besides, we want to promote and facilitate the usage of reclaimed wood. The basics of how to prepare reclaimed wood for the prevention technique can be found at the end of the article.

Based on our experience and research, this article aims to give guidance regarding sustainable and environmentally-friendly techniques to protect wood against pests, humidity and fire. What techniques fit best for your projects can be traced in the decision tree below.

Protection Techniques

Exterior and interior wood are exposed to very different conditions. Whereas both need to stand fire and pest, the wood outside is prone to much more risks as it may have to withstand heavy rain, persistent humidity or high-levels of sunlight radiation. In our projects we usually use applying borax and linseed oil for interior wood and the Japanese technique of charring wood (shou sugi ban) for exterior wood. Depending on the conditions of the property and on the available resources, a combination of techniques may be suitable.

CHARRING WOOD

UseProtectionLimitationExterior and interior wood;
preferably cedar, pine, marble, hemlock or oakagainst humidity
against pests and fungi
enhancing fire-resistance
sunlight-protectionnot suitable for glued and easily cracking wood

Charring Wood is a Japanese technique which originated in the 18th century, known as Shou Sugi Ban. The surface of the wood is burned until carbonation of the surface. The finished result is called Yakisugi. We already published an article about the technique’s history and contemporary use in architecture today, check here.

Counter-intuitively, charring wood has several astonishing advantages without involving any chemicals. The idea is to burn the surface of the wood without combusting the whole piece. Besides giving the material an interesting and unique look, the process lead to a triple protection:

fire protection – this might seem counter-intuitive, but the burning of the surface starts a carbonation of the material and thus lower the thermal conductivity. The treated material will take more time to burn in case of a fire than the regular wood.
termite and mold protection – burning wood destroys the nutritional value to insects and fungi, that regular wood gives to these species. Thus it helps to prevent the propagation of pests.
water protection – the enhanced carbonation gives the charred layer a waterproof resistance, as water slips on burned wood like over an oily surface.

TRADITIONAL STYLE
(suitable for a certain amount of similar boards)

Traditionally the technique is used with Japanese cedar. Cedar is usually the easiest species to burn because of its natural chemical properties and wide grain patterns, making it a more porous wood. In the last few years, the technique has been popularized in western countries and extended to other species of wood like pine, hemlock, maple, or oak. We used pine and beech, but we experienced that these species tend to show cracks when charring. Before burning other species of wood than the ones mentioned above, it is advised to research on previous experiences or make small prototypes. It needs to be mentioned, that once the piece gets charred, it may contract slightly and change its shape as it loses humidity. If working with very precise measurements, this needs to be kept in mind!

Following, the article is highlighting different approaches to do the burning process. For both it is recommended to choose a well-ventilated place, preferably outside, but to avoid breezes. Safety measures should include a nearby fire extinguisher, a bucket of water as well as fire-resistant gloves. Wearing flammable clothes like polyester, sawdust or any flammable items within the close surrounding must be absolutely avoided.

Traditionally in Japan, shou sugi ban is performed by bonding three planks of wood to form a long triangle and starting a fire in the resulting tube. This technique is suitable to char a bigger amount of similar boards (e.g. for cladding). The easiest way to create this triangle is to place the three boards next to each other on the ground with facing the sides to be charred upside and then folding the two outside boards upwards. The triangle can be easily fixed with wire.

One possibility is to put the triangle on a non flammable floor and start the fire at the opening at one side of the triangle. In the best case, the fire spreads over within the whole tube and it will take a few minutes to char the surfaces of the wood. Once the surface is sufficiently burned, the planks are separated and thrown to the ground to stop the burning [2]. The other possibility is to start the fire while the triangle is standing up. Therefore a stable and fire-resistant base (e.g using bricks) is advisable, best next to an also fire-resistant wall. Besides, a fire-resisting spot where the hot and probably still burning triangles can be placed later, needs to be prepared. The wooden triangle can be placed in a slight angle to the wall and the fire can be started inside the lower opening of the triangle. It is also possible to put a grill on the fire-resistant base and start a fire in there, keeping the fire slightly smaller than the hole of the triangle. That way the triangles can be just put on top of the fire and the process will be started. Once the bottom part of the tube catches fire, the fire will make its way to the top. After some minutes fire shoots will be visible on the top and after waiting another minute the triangle can be removed with fire tongs. Once the wood is placed on the prepared spot, the fire can be hosed off with water [3]. 

As it is can be an unhandy task to fix and loosen the triangles, we are working on a technique to facilitate the process. We are building a burning station, where you can easily put wooden boards and start a fire underneath. When the station will be refined, we will share the methodology and tools in another short article and in a YouTube-Video!

ADAPTED STYLE WITH A HANDHELD BLOW TORCH
(suitable for every form)

If the wood does not come in similar boards or if you do not feel comfortable with the traditional method, the wood can also be charred using a handheld propane blowtorch. For many tasks we worked with this method, for example burning the windows for the facade. Precautions for this method include the mentioned safety measures and the preparation of a fire-resistant spot to place the wood during and after the process.

Starting the process, the torch needs to be lit and the gas opened to the full, so the fire appears more in a bluish colour, meaning it is more concentrated and strong. A good distance between torch and wood lays between 10-15 cm, held in a relatively straight angle. (The distance depends on the torch, but it should be around the right distance when the top of the touching blue fire separates into orange flames).

Burning process with a handheld blow torch

It is recommended to move the torch slowly over the surfaces. In the first seconds, the grains will be highlighted in a darker colour and after the whole surface will turn darker. To get the full protection characteristics, the surfaces should turn completely black and the very first layer should start to get porous. After finishing all the surfaces, the wood needs to cool down.

The burning process

Charred board

FINAL FINISHING FOR CHARRED WOOD
(applicable for traditional and hand torch technique)

After charring the wood, one can clean it softly using a standard wire brush to remove the most superficial char and create a non porous surface, using the brush in the direction of the wood grain. This task needs some precaution. If the wood is brushed too much, its pores will be opened up again and thus the water protection layer might be lost. It is enough if the excess of the burn is removed and the texture of the drains become slightly visible. After the surface can be cleaned with a cloth or water or by using an air compressor. As final coating applying linseed oil is recommended (see the advantages of linseed oil more up in the article). 

CRITICAL CONCRETE CHARRING STATION
(Shou Sugi Ban without gas)

At Critical Concrete, we wanted to build up a tool with commonly available materials which enables us on the one side to charr wood of different sizes and forms effectively, but on the other hand, keep the process at very little risk and environmentally-friendly. Check out our Video about our very own Shou Sugi Ban Charring Station!

BORAX

UseProtectionLimitationInterior woodagainst pests and fungi
against humiditynot suitable for exterior wood (only combined with another technique or with a weather-proof resistant wood spieces)

Borax Crystals

Borax is composed of naturally occurring minerals that usually comes as a white powder, consisting of soft and colorless crystals that will dissolve in water. The structure of the boron, salt and oxygen molecules inhibit the metabolic processes of many organisms and therefore borax disinfects and kills unwanted pests and insects [4].

Be aware, that even if borax is a completely natural product, it doesn’t mean it is completely safe to manipulate. For sensitive people, contact with borax may lead to skin or eye irritation [5]. Even though borax enhances the woods protection against humidity, borate protections are only suitable for indoor wood that is protected from weather.

To prepare the solution, the mineral needs to be dissolved with water. We experimented on different percentages and concluded that the mix of 10% of Borax and accordingly 90% of water seems to be the most suitable division. When doing the mix, the water should have a temperature of around 40 degrees, so the mineral dissolves faster and in a higher quantity into the water.

Before applying the borax-mix, the wood needs to be cleaned with a wet but tightly squeezed fabric (to prevent the wood from absorbing more water) to remove dust and dirt. Just before putting the borax-water mixture, it has to be stirred again, because the solution will start settling after some time. To ensure not to apply too much water to the wood and to avoid running noses, it is recommended to wipe off any excess liquid of the paintbrush. To guarantee the effect of the borax minerals, a preferably homogeneous coverage is important. The borax must be fixed with a layer of oil, stain, lacquer or wax. (Look at the next step where we explain why and how you should use linseed).

We have to admit that using Borax as a termite repellent is the best solution we found so far, but that from a sustainable point of view it is far from perfect. The biggest and commercially most important sources of Borax are found in California and Turkey; minor resources can be found in Romania, Bolivia, Chile and Tibet. For us in Portugal that means on the one hand long transportation ways and its unsustainable consequences. But on the other hand and probably much worse the exploration of the minerals from deep layers in the earth can cause immense and devastating damage to nature and landscape. For this reason we are investigating alternatives such as wood ash mixes.

ORANGE OIL

UseProtectionLimitationInterior & exterior wood,
termites-infested woodagainst dry wood termites

Besides borax, orange oil has to be proven environmentally friendly repellent. Deriving from the skin of an orange peel it saturates the wood and gives it a shiny appearance. Thus the efficiency of orange oil against termites is debated. Some sources declare that it kills dry wood termites, but it fails to fight subterranean termites [6]. We applied little amounts of orange oil several times in a row to localized termite infections with a serine and in our case orange oil proved to be very effective. Orange oil is expensive (4 liters for around 100 €) but you never need a big quantity. For small surfaces and already infested areas it is a proper substitute for borax.

In our project we also use 5% mix of orange oil with linseed oil to protect our interior wood from future infestation. But bear in mind that if the borax will remain on your wood permanently, the orange oil would probably slowly be absorbed and loose effect with time. To our understanding it works better as a treatment than as a preventive measure.

LINSEED OIL

UseProtectionLimitationInterior & exterior Woodagainst humidity
sunlight-protection

Linseed oil exhibits many advantages and thanks to its non-toxicity and its environmentally-friendly characteristics is coming back into force lately. It can be used inside and outdoors and act as a protection for water and sunlight [7].

It penetrates deep into the wood, so it does not only saturate the surface but the whole piece of wood. It is also suitable to lock the layer of borax. It lends a golden hue to the wood which will turn to amber over time. The colour is a question of taste and due to its long drying time linseed oil may not be everyone’s favorite. But in fact, it is possible to reduce drying time by using double boiled or polymerized linseed oil [8].

Comparison between a beam with and a beam without linseed oil

To apply linseed oil is very easy, a surplus of oil needs to be wiped off from the brush before applying it to the whole wooden surface and after it needs two to three days to be completely absorbed by the wood.

Linseed oil has the advantage that it penetrates relatively deeply into the wood. But it is also possible to replace all the air contained in the wood with linseed oil. The technique uses first a vacuum to cause the air in the wood to be drawn out, followed by pressuring warmed up linseed oil into the wood structure. Once the oil has hardened, the wood cells should be prevented from absorbing any moisture. For now, this technique is common among instrument makers; at Critical Concrete we did not have the chance to experiment with it so far, but we will do in a close future (stay tuned for upcoming articles).

WOOD VACUUM STABILIZATION

Usually, this technique is done by using a sealable container and a vacuum-pump. The container is filled up with linseed oil, some sources recommend a 2:1-mixture of linseed oil and turpentin. One or more wooden pieces are put into the oil, the container is sealed and and the vacuum pump is started, going to a maximum pressure of 90 kPA (for less fragile parts the optimal maximum vacuum pressure needs to be evaluated). The second phase involves compressing the air up to 75 psi and isolating the container. It is recommended to heat the oil to a temperature around 35 degrees to prevent the oil from “boiling”. The whole thing should be left like this for about a day. After, the heating can be turned down and before starting the depression the oil should cool down for a few hours. When everything has cooled down, the pieces can be taken out of the oil. It is necessary to keep the wooden pieces in a cold environment and give them a daily wipe for the following days, as the oil may continue to sweat and thus leaving ugly patches which will later on be hard to remove. After this activity has terminated, the pieces can be removed to a warmer place to speed up the drying process (which can also involve many days). It is still questioned whether this technique is suitable for bigger pieces of wood, as we could only find examples for smaller pieces (as seen in a construction context). It has to be evaluated whether the oil can penetrate completely into big pieces of wood and if yes, if it can also dry completely. Besides making the wood waterproof, the vacuum pressure treatment adds to weight, stability and resilience of the wood [9].

LIME AND WOODEN ASHES

UseProtectionLimitationContact between ground and woodagainst subterranean termitesnot applicable on wood

Both lime and wooden ashes are alkaline, and termites do not prefer alkaline environments. This mixture was already used in ancient China, where it was usually spread on the soil to kill subterranean termites, which can also be helpful to avoid wooden construction to get in contact with termites via the soil [10]. Besides, we found some suggestions to put ashes directly in holes that derive from termites. Also a study from Uganda shows that wooden ashes (sometimes mixed with pepper or cow urine) applied to the trees and soils kept the termites away [11]. For now it seems like it is not directly applicable to wooden surfaces, because the wood’s ph is usually acidic and these of ashes and lime are alkaline. Whenever acidic and alkaline components come into contact and water is present a chemical reaction will occur. It might have been possible to predict the reaction if bringing together only a few inorganic compounds, but wood consists of a multitude of organic compounds which differ even from species to species [12]. Thus, it might be an interesting field to experiment in the future.

DDITIONAL OPTIONS SUPPORTING TERMITE-FREE WOODEN CONSTRUCTIONS

Termite-eating Worms and Fungus. There is also the possibility to attack subterranean termites (which might flow over to wooden constructions) while placing a special species of microscopic worms into the soil next to the construction – Nematodes. They come as parasitic roundworms and they will quickly find and enter the host insect’s body and start eating it from the inside. Doing so, they are releasing gut and the termite will suffer from blood poisoning and quickly die. Nematodes will go on to its next victim till they cannot find any host insect anymore and then die. Similar working species of fungus exist, too [13]. If these worms may have any potential to be put directly into a wooden construction or if they will act as a pest themselves (as for example Bursaphelenchus xylophilus does to pine trees)needs further examination.

Diatomaceous Earth. Consisting of small decayed organisms, which have dried out and become razor sharp cut the sensitive, outer shell membranes of small insects. After the insect’s shell is sliced, the extremely dry particles of the diatomaceous earth actively dehydrate and thus kill the insect in a short time [14]. Diatomaceous Earth is commonly used to kill existing pests by spraying the powder to the infested areas. If and how it is applicable as a preventive protection to be applied to the wood needs to be examined.

Sunlight. Termites might die when they are exposed to sun radiation and heat. So, furniture or pieces of wood which are mobile and where indicators of termite infestation can be indicated, might be without termites after they were put for some time into direct sun [15].

Termite traps. The favorite dish of a termite is cellulose, that is why they are craving for wood and everything which is somehow made out of wood. Cardboard boxes provide an ample amount of cellulose. If the infestation of termites is apprehend, setting out a wettendend cardboard box can lure them out of their hiding. This way will probably not lead to the total extinction of the termites in one place and it needs repetition from time to time, but every termite removed is a good termite [16].

Protective measurements deriving from the construction details

The protection of wood can be enhanced the way it is – installed in the construction. On vertical boards the water can flow more easily and thus will penetrate less into the structure. Another strategy can be to work with a ventilated wood and batten structure, securing a constant ventilation on the exposed wood. This is traditionally used in barns and today adapted to many contemporary wooden construction. If possible, exposed joints, screws and nails should be avoided, reduce possible enter spots for humidity and to obviate rusty spots.

Conclusion

Due to its environmentally-friendly characteristics and its easy-to-work with features, wood is one of the most important materials in our projects. To protect this precious material and to enlarge its usable life-circle, we discovered the mentioned techniques as the most suitable for us. One the one hand, those methods enable the protection of wood with commonly used tools or with very little acquisitions. On the other hand, they not just renounce spreading toxic material into the environment, they also prove that wood can be a durable construction material, which can replace other, less sustainable materials. Nonetheless, those techniques are not exclusive when it comes to sustainable and ecological wood protection techniques, but using these methods set incentive for a more sustainable architecture.

Building the green roof structure

BONUS-TRACK

Depending on if and how the wood was used before, the wood may need to be prepared before applying the protection techniques. This possibly includes cleaning and smoothing the wood. 

Notice: Before starting to work with wood, it is important to check the humidity of the wood (max. 20% – it is possible to use hygrometer or by comparing the weight of some size and species of wood). If the wood is too wet, it is not possible to work with it, otherwise all the effort will be in vain, you’ll damage your tools, and the wood is probably highly damaged already.

CLEANING THE WOOD

When using leftover wood, it most probably shows traces of its former life, including left-over nails, screws and other applications as well as old (and probably chipped and multilayered) paint. In case this “vintage style” is wanted, it is important to weigh the aspired look against to what extent the wood needs to be protected. Removing the leftover screws, nails and other applications will facilitate the following steps. To get rid of the paint, we suggest two tools: the classical scraper or a piece of broken glass.

When using the scraper, it is crucial not to use it in a steep angle, even if this may work more efficiently. Instead using it in a shallow angle and trying to get the scraper under the paint to protect the underlying wood from scratches.

Scraping paint by hand

Measuring

A suitable piece of broken glass for this task has a curved side. For some kind of paint, thinner glass may be more efficient, but the thinner the glass is the more likely it is to break. Also it may be more handy when the piece of glass is a bit bigger (around 10-20cm), but depending on its thickness it is also more likely to break.

It may appear that it is easier to do this task without gloves, as it brings more precision in your hands. Before taking off the gloves, changing to more tight-fit gloves can probably solve this issue. 

Changing between scraper and different pieces of broken glass, in some areas one or the other may work better. Independently of the chosen tool, the scraping off of old paint can be either an easy task if the paint happens to be brittle and already chipping, or in the worst case it can take hours.

SMOOTHENING THE WOOD

After removing the nails the wood probably looks dirty, but also new wood may also have a layer of dirt, bark or mold covering its surface. It is important to clean the surface well to make the wood receptive to the following wood-protection treatment, for example to ensure a better infiltration of pest-protection and oil. An additional advantage of the removing of the first layers is the beautified appearance of the new wood surface.

The removal of the top layers and smoothing of the surface is achieved by sanding or planing. Of course there is the possibility to sand by hand, but unless it is not a very small wooden surface that you need to be protected, it may be really better work with a sanding machine. 

While using the sanding-machine, it is crucial to put the sanding patch or belt as flat as possible on the wooden surface (of course as long as this is manageable with the kind of surface you have). It may appear that it works faster and more efficiently when the sanding paper is touching the wood at an angle. But on the one hand it ruins the result as the surface will not turn out straight and bumps can be easily created. On the other hand, it also ruins the sanding pad at the edges.

Sanding

Little corners, that cannot be reached with the sanding machine – or while using the machine could come close to very weak parts – need to be sanded by hand, or a multi-tool if you have one! The worn out patches of the sanding machine probably can be used for the parts which need to be sanded by hand.  

Now the wood is ready for protection!

Sources

[1] NZ WOOD “Which building material performs better in a fire – wood or steel?”, [Online] available at http://www.nzwood.co.nz/faqs/which-building-material-performs-better-in-a-fire-wood-or-steel/ (Last accessed in January 2020)

[2] Shou Sugi Ban “Shou Sugi Ban 101”, [Online] available at http://shousugiban.com/shou-sugi-ban-101/ (Last accessed in January 2020)

[3] Instructables “Backyard Shou Sugi Ban”, [Online] available at https://www.instructables.com/id/Backyard-Shou-Sugi-Ban/ (Last accessed in January 2020)

[4] ThoughtCo “The Chemistry of How Borax Works as a Cleaner (Sodium Borate)”, [Online] available at https://www.thoughtco.com/how-does-borax-clean-607877 (Last accessed in January 2020)

[5] Healtline “Is Borax toxic?”, [Online] available at https://www.healthline.com/health/is-borax-safe#safety (Last accessed in January 2020)

[6] Networx “Does Orange Oil Work for Termites?”, [Online] available at www.networx.com › article › does-orange-oil-work-for-termites (Last accessed in January 2020)

[7] The Craftsmen’s Blog “How To: Use Boiled Linseed Oil (Safely)”, [Online] available at https://thecraftsmanblog.com/how-to-use-boiled-linseed-oil-safely/ (Last accessed in January 2020)

[8] ARDEC “Linseed oil, a natural solution for Wood Finishing”, [Online] available at https://ardec.ca/en/blog/22/linseed-oil-a-natural-solution-for-wood-finishing (Last accessed in January 2020)

[9] Good Bagpipes “Vacuum and pressure oil treatment of wood”, [Online] available at https://www.goodbagpipes.com/index.php/about-me/writings/pipe-making/131-vacuum-and-pressure-oil-treatment-of-wood (Last accessed in February 2020)

[10] Abdalla House “Termite deterrents”, [Online] available at https://www.abdallahhouse.com/2009/11/termite-deterrents.html (Last accessed in January 2020)

[11]P. Kiwuso, G. Maiteki and J. Okorio “Indigenous methods of controlling termites in agroforestry in Uganda”, 2015, Kampala, Uganda

[12] Passivhaus “LA PRESERVATION DES BOIS DANS LA CONSTRUCTION” [Online] available at https://passivhaus.fr/wp-content/uploads/2017/11/traitementsalternatifsdesboisdeconstruction-1.pdf (Last accessed in January 2020)

[13] Varsity termite and pest control “All-Natural Ways of Eliminating Termites” [Online] available at https://varsitytermiteandpestcontrol.com/natural-ways-eliminating-termites/

[14] Citypests “Diatomaceous Earth for Termites”, [Online] available at https://citypests.com/diatomaceous-earth-for-termites/

[15] Pesthow “How to get rid of termites”, [Online] available at https://www.pesthow.com/how-to-get-rid-of-termites/

[16] Pesthow “How to get rid of termites”, [Online] available at https://www.pesthow.com/how-to-get-rid-of-termites/

[image by Vincent van Zeijst], [Online] available at https://commons.wikimedia.org/wiki/File:Faroe_Islands,Streymoy,_Kirkjub%C3%B8ur(1).jpg (Last accessed in January 2020)

The post Natural Wood Protection first appeared on Critical Concrete.
Did you miss our previous article…
https://www.thevisualconcretegroup.com/?p=250

The advantages of using residential pavers over commercial or industrial paver stones are numerous. The primary difference between the two is that residential paver stones have a matte finish and are designed for comfort and ease of movement. They can be installed on paths, driveways, and even garages. Pavers that are made from cement, asphalt, and concrete are recommended for more intricate designs.

When it comes to driveway paving, no other material can offer the durability and dependability of permeable pavers. A typical permeable paving company will use the best materials in the market for your project. The cost for this type of paving is considerably less than others. If you are going to build a brand new house or rebuild an old one, then you can always use permeable pavers. The following are some of the many advantages of this type of paving:

Driveway Paving – Many people prefer residential pavers over asphalt because they are easier to maintain. For one thing, you don’t have to put asphalt on top of the ground before you install the paving. All you need to do is lay the actual paving, apply some asphalt shims and then just sweep away any debris with a broom. Asphalt driveways need to be resealed at least once a year to ensure their durability. Concrete driveways are also durable and easy to maintain.

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Effective Use of Flagstone – When you use residential pavers on your walkway, you get a beautiful and highly functional material that looks like stone but is much more affordable. It is the ultimate answer if you are looking for a low-maintenance driveway that still offers a look of elegance. The cost of flagstone is considerably lower than asphalt and you don’t have to wait for it to dry like you need to do with asphalt. You can even install the flagstone yourself without seeking outside help. You can be the one to select the type of flagstone that suits your needs.

Four Foot Pavers – For a perfect walkway, you may want to hire a mechanical install machine to do the job for you. The cost of a mechanical install machine is a bit higher than when you use residential pavers, but it will save you time. You can go from door to check out the effectiveness of the paver. If you need to move it elsewhere, a four-foot paver will do the trick. There are four-foot residential paver types that can handle heavier shoes or objects without getting stuck.

Large Paver Patio With Columns and Built-In Gates – This outdoor space has plenty of seating, dining and other facilities. The large paver patio with columns and built in gates are ideal for gatherings. The patio area is enclosed by a durable and attractive gazebo that features a four-foot deck and screened in windows. The four-foot-wide and deep pedestrian ramp provides easy entry and exit for your guests. Its screened in windows also serve as a great place to keep the heat in during the winter months. The patio is finished with a lush outdoor carpet and includes an assortment of comfortable furniture pieces.

The perfect blend of beauty, function, and style, a two toned paver walkway with a grey block trim and a large paver patio with columns and built in gates will certainly make your home more attractive. It offers complete privacy and enjoyment. It can also enhance your property’s value. Your backyard can be transformed into a tranquil oasis, a place where you can enjoy good food and rest, and it can also become a great hangout for your family and friends.

Cork forests

Portugal is not only known for good wine and beautiful beaches, it is also the largest producer of cork, more than 50% of the world supply comes from this country, before Spain, Morocco and Algeria.

Map of the location of montado © APCOR

Natural cork originates from of the bark of the cork oak tree (Quercus Suber), which is indigenous to the Mediterranean region and northern Africa. The first harvest of a tree can be made after approximately 25 years and the bark renews itself naturally every 9 to 12 years. The cork oak forests in Portugal, called Montados are an important contribution to the biodiversity and balance in the ecosystem. The cork is present throughout the country, but especially in the Algarve and the Alentejo plains, and occupies 22% of the country’s forest area.

It is important to preserve these forests, because it is home to a number of mammals, reptiles, birds as well as the Iberian lynx, the world’s most endangered feline species. The montados are part of the Portuguese cultural heritage and contribute to the regional identity.

Properties and uses

Cork has some remarkable qualities and can be used for many different purposes, it is even applied in space as thermal insulator for space shuttles. It is light, durable, elastic, waterproof, fire retardant and has great insulation properties. Furthermore, it is 100% reusable. The structure is composed out of tiny gas-filled cells, creating a huge disproportion between the volume and the weight of the material, more than half of its volume is air.

These properties make cork incredibly useful as a building material, whether as flooring, insulation sheets or surface finish. The cork can have different shapes: insulation panels, coatings flooring, cork stoppers, composite agglomerates, raw material. 

If the material is used raw and 100% natural (if the process is free from chemical substances), it can provide an ecological alternative to conventional solutions, not least because of the barks ability to absorb CO2 during the regeneration process. Regularly harvested cork trees store 3 to 5 times more CO2 than those left unharvested.

THE PRODUCTION PROCESS OF CORK INSULATION

Working mainly on architectural projects in the North of Portugal and looking for a local material to integrate a vernacular approach, we were interested in the potential use of cork in construction.

We recently had the opportunity to use this wonderful material in two important projects and with different applications. In this article, we will describe the cork applications we tested and the methodology we used.

Like all our research, we paid attention to have the most sustainable applications with: relatively low cost, simple process and possibility to re-use the cork panels.

ADVANTAGES OF CORK INSULATION100% natural and fully recyclableExcellent thermal and acoustic insulationEasy to apply ( However, cork is fragile)Mechanical stabilityGreat behavior in large temp. range (-180ºC to +120ºC)CO2 sink (Carbon Negative)

INSULATION WALLS AND ROOFS WITH CORKS

The walls

Currently, we are finishing the renovation of a modest house for a family as a part of our Post-Graduation in Sustainable Architecture, in partnership with the municipality of Esposende.

In order to improve ceiling height and spatial quality, the roof was taken off and made new. We used the opportunity to insulate the new roof and built an exterior insulation system on the walls that had none. Like many buildings in Portugal, the Esposende house did not have any insulation .

The challenge was to find an economic and ecological solution to improve this. In the case of the rehabilitation, we faced a series of challenges:

The walls were far from being anything close to straight.We wanted to avoid the glues and mortars that are very often used in cork solutions in architecture (like in the ETICS system).

 Aerial view of the wall insulation system

So we used this cork insulation system:

1. Regularize the walls a bit, enough to limit protuberances from the wall from the line we aspired to follow.

2. Setup vertical supports on the wall, starting from the edges, following three horizontal thread lines, in order to transform a twisted wall into a straight support for our system. To protect the wood, we have applied a mix of natural oils (Read more about natural wood protection in this article)and have placed 5 cm stone wedges under the wood to avoid any contact with the floor and prevent it from rotting. Between each of these posts will come the 5 cm layer of cork.

3. Cover the walls with a first layer (1 cm) of cork, below our vertical supports fixing them with screws and wall plugs directly in the wall. A thin board is better to fit the shape of the walls without leaving empty spaces. This layer is thought to prevent thermal bridges between the 5cm layer of corks coming next. For this reason, the two layers should overlap in a tile fashion.

4. Superpose another cork panel of 5 cm on the first board and between the vertical battens. Making sure to have continuous overlap between the two layers. 

5. Fix horizontal structure on the vertical ones every 40-50cm from each other to hold the cork panels (5cm). These horizontal support will allow a wedge to sit between themselves and the 5cm cork boards, to secure the ventilation of the system and pressure the cork boards together and bear the board and batten system.

6. Set up the board and batten system on top of the horizontal structure set up in point. Depending on the wood you’re using, avoid putting two screws horizontally on the boards to avoid cracking. The boards should be free of movement and have at most one or two nail/screws set up on the vertical plane. The battens are the one pressuring the boards in place.

The roof

For the roof, we optimized the use of material to ensure the most sustainable application, as with the walls. Thus, we only used four layers: corkpanels, vapour barrier, wood and finally roof tiles. We used a corkboard of 8cm with overlapping joints to secure the potential thermal bridges. The cork boards used for the roof are overlapping to avoid thermal bridges. From the original 1000*500*40mm boards, the manufacturer cuts out 40mm on two perpendicular sides to allow the overlap. 

We decided to follow the sarking technique. The sarking method allows us to have a continuous and homogeneous insulation, without thermal bridges due to the frame.

And internally we benefit from the timber structure that can be seen inside the house!

Roof insulation system

Here are the different steps: 

Lay the cork board directly on the rafters. We used very thick cork panels to avoid using OSB as a roof support. These panels made of sheets of resinous wood assembled by a synthetic resin have the defect of not being very breathable. Cover the cork panels with a vapor barrier, this material is used for waterproofing to prevent interstitial condensation of the roof and finally to allow eventual humidity to go out. Grid the roof with vertical and horizontal battens. They will serve as a support for the tiles and will allow a complete ventilation of the roof. Set up the tiles.

GREEN ROOF WOTH INSULATIVE CORKBOARD WITH INTEGRATED DRAINAGE SYSTEM

We decided to use cork for another architecture project last year, a sustainable green roof. A vegetal roof of 140 square meters covering all the top of the workshop. In this article, we will only explain why and how we used the cork, but if you want to learn step by step how to build a green roof, we advise you to watch this video. 

We used cork for a triple goal: insulation, drainage and water retention, in partnership with Neoturf, who investigated this possibility and designed the board. The grid on the top side of the board was meticulously designed to allow for a high flow of water drainage. It is necessary for a roof to withstand frequent torrential dumpers and by using this system, we negate the need for synthetic insulation and plastic drainage cups.

These cork boards provide insulation with a thermal efficiency of 0,038 à 0,040 W/mK* on average, which is comparable with material with synthetic sources such as expanded polystyrene.

On the top, to protect the cork from the plant’s roots and substrate a geotextile is added to prevent silt and other particles from the substrate from clogging the grid drainage system within the cork. Activated clay balls surround the borders of the walls, windows, and wooden barriers, and provide additional drainage and fire protection.

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