Hi Chaps I've got a 15 house contract coming up soon which comprises an engineered oak board to the hallways and kitchens, and carpet elsewhere. I was going to dpm and latex the wood areas (which are on underfloor heating btw). I priced based on Tremco ES100 DPM and SX302 latex without giving it much thought, but now i'm wondering how to tackle it due to compressive strengths - the oak is to be fully stuck with SF520 MS Polymer adhesive. I don't have enough money in the job to stretch to a water mix but see that the compressive strength of the 302 is only 25nm. It also seems according to other manufacturers such as F.Ball that this figure is only achieved after a month which worries me. I've spoken to my Tremco rep and he suggested not latexing at all ie DPMing direct to the subfloor, then sticking the wood to the DPM which after dismissing it to start with i'm beginning to think might be a good idea. The individual areas are quite small mostly no more than 8-10sm each but in total are about 220sm so i need to make sure i'm minimising any risk in terms of floor failure. Can any of you chaps give your thoughts on this please? It's a 50k+ contract so i want to get it right but at the same time i didn't really want the extra expense associated with a water mix, unless anyone can suggest a cheap one that's no more than about **** prices in trade section only please Cheers.
Check if you can use a DPM on ufh. If the floors flat and solid you can bond direct to subfloor. What screed is the builder using and how thick?
Engineered wont move like a solid so you should be ok? If the floors flat definatly bond direct to a Dpm, I've done it loads of times. Problem is the ufh. Any movement in the subfloor and the Dpm is knackered.
You cant use a surface dpm over underfloor heating ! (odd manufactorier says you can but its not the dpm that fails, its the concrete that fails especially when a wooden floor is bonded to it, concrete failing is not a dpm failer so no come backs.) You cant install solid wood over UFH ! (only engineered) You require a compound strength of 25nm +. Mapei Latex plan trade comes in less than you have quoted and has a 30nm strength. It will get to 24nm within 7 days. The wood wont be moving in such a short period of time so you will be ok. Make sure you leave the compound for a couple of days tho. (ask in trade section for prices and where to purchase) You require a surface dpm under ALL solid wooden floors. The BS standard requires the subfloor for BONDED wood to be below 65%RH.
Cheers for the reply. Tremco and Laybond both specify their one coat membranes as suitable for use over underfloor heating. I hear where you're coming from but what choice do i have? To finish the job on time i'll have to use a dpm. Also i'm not laying solid wood, i'm using engineered so should be fine on ufh.
Engineered should be fine. As for the dpm???? I hope so! Do you have a RH reading of the subfloor? if low 80's im sure you will be o.k. But as above, you know yourself the risk your taking. good luck
Yeah i'd forgotten about K11, that is pretty reasonably priced if i remember rightly, cheers for that. Latexplan trade is certainly worth considering too i've used it in the past and is similar cost to tremco 302. I like to use matching dpm and latex where i can though just in case i get problems.
the new mapei 1 coat can go over underfloor heating providing your not bonding wood to it. I think sticking with a system dont really matter with what your doing as you will be installing with out a guaranty anyway. The guaranty will lye with yourself. However if mixing systems then you 100% void any warranty of there was any chance you could claim.
This looks interesting, will get a price on the dpm today, cheers. I'm assuming that K11 can't be used under the dpm, there's no mention of it either way on the ardex datasheet?
It can't mate. You could ultra floor level it 2 under and over the ardex dpm 1c. That's what I do to keep the cost down.
