Eliminating Steel from a Home’s Structure

Elimination of Steel as part of a Home’s Structure

Laminated Wood or Bamboo beams for rafters and joists.
These are a far superior solution for structural needs that although be it rare in Costa Rica, is far more economical than steel, incredibly strong, much more stylish as well as a far better environmental solution. Eg. 1 cubic meter of wood consumes one ton of CO2 when growing versus steel that creates 1.8 tones of CO2 hence the impact is almost triple in difference. Aside from that lets look at the other benefits just bare with me as this requires a detailed explanation so as to understand just how this makes an excellent option for well informed consumers..

Glu-lams as they are called, is a very common solution in North America for building excellent structures but few use them in Costa Rica due to both the level of ignorance of the application of such as well as known availability. You do not just go grab them from the local fereteria!
We have adopted these as our own preferred structural material for our own homes for the following reasons as well as offering such for sale as well as our consultancy to consumers who seek superior solutions in both quality, price and as a green building method.

We are also just in the process of incorporating the use of bamboo as well since there is huge tracks of bamboo inventory available which is substantially stronger than wood, grows much faster (4-5 years) and consumes as much as 4 times the CO2 hence it makes an ideal construction material. The harvest of bamboo culms does not affect the plantation at all since we selectively harvest only the mature leaving behind all the immature culms and of course the root structure that can continue producing bamboo crops for up to 120 years. This means there is no environmental destruction in the harvest process at all plus no erosion to precious soil structures can occur which is very critical in flood prone areas and mountainsides. Plus we get a beam substantially stronger than both steel and wood.

Available materials suitable to make Glu-lams are bamboo as well as the hardwood species of teak and cedro all of which have the common critical characteristic of being termite safe materials that are not suitable lunch material fpr this army of enemies.

Comparing Glu-lams to Steel:

For those who would otherwise be considering steel for a roof/floor structure as an example here is a simple comparison. 1 meter of 2″ x 6″ costs $8.50 – $10.00 depending on species versus at least requiring a doubling of purlins would be required to support the same load would cost $8.33. Pound for pound laminated is stronger than steel. Also take note the superior longevity if you are building at the beach where there is the oxidation factor on anything metal versus wood which is impervious to air born salt. Plus ugly purlin is always hidden away versus wood structures can be accented to add beauty in your exposed roof structure. Go to our renovation page and you can see an example of a Pagoda roof we built in Santa Ana to cover an open terrace. Win the client loves here laminated wood. We find with our clients that this is always a major concern hence the much preferred method.

Comparing Glu-lams to a solid single piece of wood:

There is two issues at hand here, one is responsible inventory management and the other is strength and quality of the final product. First off dimensional hardwoods are getting harder and harder to locate since it requires very large trees to produce such since to cut good 2″ x 6″ (the most common size) takes a tree trunk diameter of 16″ to 20″ to produce good structural material. We are talking about old trees (25-120 years under ideal conditions) which are disappearing quickly hence actually finding it can be difficult and such simply does not exist in young plantations. That is drastically different as compared to using much younger (10 year old) plantation grown trees/bamboo (5 year old) where we only need 1 1/2″ x 3/4″ pieces to make up the lamination stock hence the raw material is muuuch cheaper with a never ending inventory available. As a result of global demand prices for premium wood just keeps going up due to this scarcity hence this wood from older trees costs much more since you are basically purchasing time. It just simply is not responsible forestry management nor economical to take mature hardwoods to use for dimensional lumber. In fact is is basically loco.

Quality – The second issue is solid wood no matter how old it is just is not nearly as strong as a Glu-lam is, in fact it is common to be able to reduce the beam size by 40% when laminated hence we consume way less wood to do the same job. The other big problem is very few sawyers have kilns to properly dry the much thicker woods to make stable dimensional lumber hence it typically shows up on the job site soggy wet as no one is willing to wait the 3 years it will take to properly air dry it. The inevitable result is this, there IS GOING TO BE a number of pieces that are going to come curved or twist or crown after they are installed creating big problems in the structure they are part of. Even with kiln dried materials used in Canada the whole industry has gone away from solid floor joists in favour of laminated, engineered TJI or web trusses that never do this hence no warranty problems for the builder or owner plus reduced timber consumption. Converse to this a laminated beam comes to the job site perfectly straight and six months later it will still be and 66 years later it will still be so. Hence such is much easier for the builder and muuuuch safer for the owner. Also solid materials will always have cracks showing up over time as they dry out and the bigger the dimension the worse it is, versus laminated which will never develop cracks.

Comparing Glu-lams to concrete floors:

For second story floors there is really no option since a concrete re-inforced floor costs $85 to $110 per square meter to construct plus adds a minimum of two weeks to buildout time for a 100 m2 floor. So a lot of money and time spent versus a wood structure will come in at roughly half price and be built 5 to 6 times faster. After the fact wood floors have the desired amount of spring in them to reduce stress on feet and knees as we walk on them as well as being considerably quieter with far less noise transfer. This is very important even on first story floors where the owners want a more forgiving floor to walk upon. Many may choose to cover such structures in mature Tico hardwoods so as to enjoy their beauty for years to come which makes for a much smarter use of mature hardwoods than for dimensional lumber. Also on sloped lots wood is easier and often cheaper to build out on a support structure versus trying to level off a mountainside with sloped building sites. This can make for much less dirt movement and less future water erosion problems. Posts of wood or concrete columns can much easier be built to accommodate such a situation than either cutting into a mountain or building up with fill to support concrete slabs. This also drastically reduces the need for use of concrete hence so reducing it horrible environmental impact as well.

All in all a real win/win/win situation. Better price, better quality, more comfortable home utilizing far superior green building principles.

Regards,

Trevor

About Trevor

I have lived in Costa Rica for 14 years and have been active in real estate development over that period and construction in general. I am a qualified Journeyman carpenter and cabinetmaker from Canada. My current focus project is building custom green homes and housing packages all built out of Magnesium Oxide SIPs.

Comments

Eliminating Steel from a Home’s Structure — 4 Comments

  1. The price per square meter on second story concrete floor seems high at $10,000 for 100m2. Using a product from Metalco, can space beams 1.5 M per their engineering, comes in 10M lengths. So once floor structure is in place it is only a day or two of prep, if plumbing and electrical go in the pour, less if not. And then a day to pour the floor. Cost of materials is around $2500 including decking, concrete, rebar, etc. Labor maybe $1000? That is well under $50 a square, right? Just wondering how you got to the 85-110 price.

    Thanks

    • Adam,
      This answer is going to be much longer and more detailed than your question but I hope it demonstrates how and why I come up with my recommendations in the fist place.

      First off when I quote prices of anything I do not do it lightly especially since I use these same numbers to make decisions in my own business. I do not provide information to entertain you or anyone for that matter what goes in this book is exactly what I use in the real world. It most certainly is not theory. Specifically the sources those numbers come from are three people, my personal experiences, my friend Mario who runs his own traditional Costarican construction company as well as our architect Oscar Villavicencio who we have worked with for 13 years now. The combined experience is a mere 60+ years so I hope that you can appreciate that we possibly may know something and are not just winging it. Mario specifically costs his jobs at $85 a m2. Oscar uses $110. Both are current rates. The last time I built a floor in this method is a while back so I went to them to confirm current costs. I do know when I did this that these floors are not cheap at all when I used Ekstrom’s concrete beam and styrofoam block flooring system. Nor do they offer very long spans. Once you elevate any slab the price doubles to triples in costs.

      Your numbers are quite incomplete or wild estimates Eg. $1,800 for concrete alone plus pumper truck fees. Then add to that all the steel rebar & mesh required. Now add in the cost for all the beams needed plus some kind of decking system. The Q deck alone you suggest would cost $1,500 it is hardly a miscellaneous line item. Also add all the teleposts that have to be rented to support this floor for 3 to 4 weeks, plus vibrator and power trowel. Those same posts are one and the same that also prevent any work being done below them for that same stretch. Then add in the cost of all the form work to make the perimeter and intermediate beams. Then all of us confirm this would take a crew 2 weeks + minimum to build the floor and all the support structure. The actual pour is less than 10% of the required labour. $1,000 of labour, that most certainly is not going to cut it! My crew costs would run in the $4,200 to $5,000 for that job assuming of course I would ever even contemplate pissing away our valuable time on a create work project. IT IS NOT a simple matter of slapping down Q deck and dumping 30 tones of concrete on top of it. This takes a serious structural system to support all of this = $$$$ Electrical and mechanical runs being done are not exactly optional assuming your home actually needs lights and toilets so this must be included and then pray like hell no one forgets anything. IF they do then that is one ugly situation to fix in solid concrete. So we are up to $8,300 now with a whole lot more to add in yet with steel, forming and rentals to add in. Plus aside from this there is one thing that totally baffles me when an entire industry ignores the existence of job carrying costs. The owner has to pay this so it has to be included in the assessment of total construction costs as well as what various systems actually cost in the end. In this example the time taken to build this floor alone I would start with a hole in the ground and be on the roof of a two story home in the same time this slow build floor would take alone and then when done I am not sitting round twiddling my thumbs waiting for concrete to cure.

      Now lets get into the deeper crux of this discussion. The costs is but a small part of an intelligent and well informed decision on the part of the home owner. I categorically state this type of floor just simply sucks on a long term livability and quality basis. Wood floor structures are way kinder on the human body as they offer a cushion not noticeable to the conscious but most noticeable by your physiology. They are easy to remodel and easy to make corrections on. They build way faster, like about 10 times faster. They are way quieter as compared to concrete on Q deck such as you suggest are horribly noisy for the residents. Just sit below a floor with a women walking in high heels over your head and then tell me such makes a quiet floor. Wood flexes in an earthquake rather than fractures as concrete does nor would it turn you into a pancake if it did fall. Then lets not forget that wood consumes 1 ton of CO2 for every cubic meter of wood grown on the plantation versus cement that contributes 800kg of CO2 per ton of portland cement. One consuming versus one contributing so there is a vast difference in the green quality of these two types of construction materials. There is some idiots (engineers and architects included) that suggest concrete construction is green when fact demonstrates that this is far from anything that could remotely be considered truthful.

      This entire book exists to help consumers make much better decisions when surrounded by an entire industry that lives in a delusion as well as to demonstrate how to build efficiently and with a green conscience if it were not it most certainly would not exist and it most certainly would mean that I would not have invested hundreds of hours in writing it and updating it or in answering reader’s questions.

      Trevor

    • Adam,
      Now with the pictures of your project in hand I see that we are actually comparing a dumptruck to a ferrari. I specifically stated in my post “second story of a home” but you are comparing a slightly elevated slab with ground level access designed for a steeply sloped lot. This is in no way similar need, in methods, time requirements or amount of materials needed. Elevating a floor 9 ft above ground level where the concrete must come from is totally different and way more expensive hence the prices I quoted are indeed accurate and valid whereas your comparison is totally irrelevant nonsense. Also ignoring the cost of the environmentally offensive steel structure supporting your concrete floor is not at all appropriate nor a relevant comparison. You have to compare all components when comparing one system to another to come up with anything that resembles a valid answer. Just selectively forgetting critical parts does not serve a higher purpose. In fact our glu-lams would still beat the falsely lowered price that you have suggested. Meanwhile our structure provides a much friendlier floor for the owner to live upon for years to come. Not to mention a far greener solution than the old standards of concrete and steel. “If all you have is a hammer then everything is a nail.” That is what such methods remind me of versus those of us who try to think up better solutions to old problems and challenges.

      Trevor

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