Thread: floorboards as decking

gday field

laying tongued & grooved floorboards as decking... some considerations for you

decking timber will move - when it gets wet/hot it will expand and vice-versa dry/cold - you need to allow for this movement or the deck will tear itself apart. a way to do this is to have expansion joint(s) between the boards themselves - i have never done this externally but maybe someone else has. here is an article on this matter for internal flooring - being external you might make the spacings of the expansion joints closer together...

http://www.timber.org.au/resources/F...20Dec%2005.pdf

laying the boards - i think the fall of the deck must be on the same axis as the long axis of the tongues of the boards - this way water will drain from the gaps between the boards - if you live in areas that frost, the freeze-thaw cycle will be another source of expansion pressure on the deck. so a well-draining one would increase the life-span.

if think your finishing treatment will be essential to the success or failure. you want to avoid any process that will form a film and subsequently 'glue' two boards together - for the initial application you would need to do them before installation which will be easier to do all sides (you need to do the underside as well) and get well into the grooves of the boards, but further maintenance applications will need to be done in-situ, so i think that rules out sealants - i would even avoid those 'acrylic oil' concoctions - i bought an outdoor setting recently which had been treated with this stuff about a year ago - it has failed patchily on most sunward-facing surfaces but is still intact everywhere else - this causes the timber to take on moisture unevenly adding to the internal stresses, it also looks like shyte. result - have had to sand it all off and lay down some real love-juice.

when we did our deck we used a product called organoil woodguard to initially treat the decking. this product consists of oils and beeswax, which will control moisture uptake and loss, and also increase the life-span of any oil applied at a later date - i believe there are oils in this product also resist lyctid borer and fungal attacks. it seems to have done the job so far but i've not built an external deck before that has remained unsealed and so can't comment on what would've happened if i didnt do it. we also treated the entire stock - i know, for posterity i couldve left some untreated and fixed that off also, for comparison - but then, where is the guarantee that the cut of the timber was not at fault? it would require too much of the stock to be left untreated for a fair comparison - anyway, enough research has been done for people to know that untreated timber in the sun will be an issue, regardless of the treatment you use this is a necessary step in the process.

here is a wealth of info on the various species - http://www.hardwood.timber.net.au/ - go to the species guide on the top bar for some info on the types you are considering - look for anything that is class 1 or 2 durability.

the timber framing code allows for larger spans of tongued & grooved flooring, which will allow your joist spacing to be further apart if the appropriate timbers are used - this will offset some of the cost of using the hardwood flooring; you can also save further by using green-sawn hardwood with larger spans for the sub-structure.

r's brynk

thanks for you informative essay brynk! A lot of information there, also enjoyed your postings on your own deck. I'll let you know how it goes, heading down to a wrecker we know on the weekend who has cheap prices on low quantities of re-claimed flooring - bound to find something we can have a bash with. Cheers.