LA3222 Posted November 27, 2019 Share Posted November 27, 2019 I am trying to get my founds in before Christmas but it looks like weather and time is conspiring against me. I may be able to get all the sub layers done before xmas but everywhere shuts down from 20th till 6 Jan. If I get the insulation laid and all the steelwork and UFH heating pipes laid before Christmas will this be ok to leave exposed to the weather until I can get the concrete poured at the start of Jan? Not sure if leaving it all exposed will be ok or Not? Cheers J Link to comment Share on other sites More sharing options...
Red Kite Posted November 27, 2019 Share Posted November 27, 2019 I would reckon leaving it exposed will be fine as long as the UFH pipes are not full of water and might freeze and split. Also making sure you keep as much water (rain and ground) under control as possible would be a good idea (you dont want the insulation to float up) - can you set up a pump? Insulation and steel are often left out on site for weeks at a time - not much to degrade really if its EPS or similar. Concrete for the slab in Jan will probably be OK unless it gets really cold - and slabs are usually not too bad as they are a large volume sat on insulation so they dont suffer from frost damage as they set - but check with your concrete supplier. I would pressure test the UFH pipes before you pour just in case - you cant fix them easily after the concrete goes down! Link to comment Share on other sites More sharing options...
MikeSharp01 Posted November 27, 2019 Share Posted November 27, 2019 If it a passive raft you will need to keep the thing drained or you will end up with a swimming pool and it may well force the sides out. Link to comment Share on other sites More sharing options...
LA3222 Posted November 27, 2019 Author Share Posted November 27, 2019 9 minutes ago, MikeSharp01 said: If it a passive raft you will need to keep the thing drained or you will end up with a swimming pool and it may well force the sides out. The potential for a swimming pool is what concerns me. I guess there are two options, delay or buy a pump and take a chance that it will be ok! Link to comment Share on other sites More sharing options...
Russell griffiths Posted November 27, 2019 Share Posted November 27, 2019 If it’s 3-4 days to get the insulation in 3-5 days for the steel 2 days for the ufh i would get everything on site do you ground preparation and then be very ready to start again on the 2nd jan, by the 20th you will be ready to pour, no point having a spoilt Christmas rushing around with a pump that has broken and trying to find a hire shop that is open. Now im very gung ho, but it would be a shame to spoil everything over a 3 week delay. 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted November 27, 2019 Share Posted November 27, 2019 On our build for the garden room I created two holes in the DPM, at the lowest points, to let the water out into the land drain and then sealed them up very carefully with some fearsome double sided mastic tape before we put the concrete in with full BC approval. We didn't need it for the main build as it didn't rain in the final weeks and we had a deep pocket we could pump out and then bale. Link to comment Share on other sites More sharing options...
Onoff Posted November 27, 2019 Share Posted November 27, 2019 Could you create a sump/depression in the DPM to sit a (sump) pump in? Link to comment Share on other sites More sharing options...
willbish Posted November 27, 2019 Share Posted November 27, 2019 (edited) Water on top of the raft will at least hold it all down. Although depending on how much rebar is specified will do that job. I think you could just leave it all over Christmas and then pump out in the New Year. No need to run around on Christmas Eve looking for a new pump if one goes bang. Just it let it fill up. 3 hours ago, MikeSharp01 said: If it a passive raft you will need to keep the thing drained or you will end up with a swimming pool and it may well force the sides out. Does water have more ability than concrete to force the sides out? I wouldn't think that to be the case. Concrete is significantly more dense than water. Edited November 27, 2019 by willbish Link to comment Share on other sites More sharing options...
Russell griffiths Posted November 27, 2019 Share Posted November 27, 2019 I’ve obviously lost my nerve Link to comment Share on other sites More sharing options...
LA3222 Posted November 27, 2019 Author Share Posted November 27, 2019 The point about concrete being less dense than the concrete is a good one! I'm not sure how to create a low spot....in theory the insulation should be completely flat so it will be the thickened perimeter strips which fill up - may have to look into sump pumps that go all the way down to a couple of mm of water. All food for thought gents and no glaring reasons why not to do it - ta for the feedback, always appreciated. Link to comment Share on other sites More sharing options...
willbish Posted November 27, 2019 Share Posted November 27, 2019 My raft was out for sometime because it took me weeks to do the rebar cages.Wish I'd done like @Russell griffiths and bought them ready tied up. During that time (September) it rained a fair bit but the sun came out and dried things. At one point I used a wet vacuum and brush to get rid of most of the water. Only because I'd had enough of paddling around in an inch of water. It doesn't need to be bone dry for the pour either Link to comment Share on other sites More sharing options...
LA3222 Posted November 28, 2019 Author Share Posted November 28, 2019 8 hours ago, willbish said: My raft was out for sometime because it took me weeks to do the rebar cages.Wish I'd done like @Russell griffiths and bought them ready tied up. During that time (September) it rained a fair bit but the sun came out and dried things. At one point I used a wet vacuum and brush to get rid of most of the water. Only because I'd had enough of paddling around in an inch of water. It doesn't need to be bone dry for the pour either That's good to hear - my main concern was whether prolonged rain would balls everything up. Think I will probably buy a sump pump to keep the water level low and crack on with it! Link to comment Share on other sites More sharing options...
willbish Posted November 28, 2019 Share Posted November 28, 2019 I'd recommend getting some weight on top of the EPS pretty smartish because as @Red Kite has said it could float and move. 1 hour ago, LA3222 said: Think I will probably buy a sump pump to keep the water level low and crack on with it! Yep I reckon it'll be fine, especially with the thickened perimeter, gives somewhere for the water to flow to. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted November 28, 2019 Share Posted November 28, 2019 13 hours ago, willbish said: Does water have more ability than concrete to force the sides out? I wouldn't think that to be the case. Concrete is significantly more dense than water. You are right concrete adds much more pressure but its all down to how well the external face is protected along with the the depth of water behind it and I did hedge a bit with 'might'. Link to comment Share on other sites More sharing options...
willbish Posted November 28, 2019 Share Posted November 28, 2019 I had some concerns with mine that the EPS would be able to hold back concrete at 300mm deep. The EPS was 200mm thick around the perimeter and each section around 900 long with a solid profile that locks each section together. I shouldn't have had any doubts, the Isoquick system was excellent, it didn't move or bow at all during the pour. 1 Link to comment Share on other sites More sharing options...
Neil Posted November 28, 2019 Share Posted November 28, 2019 Something else to watch!! I had some 110mm drainage pipes in the stone layer within the house footprint. Both ends of the pipes had vertical upstands to rise above the finished floor levels. Following very heavy rain these pipes 'floated out'. Although I had them weighted down it took me a few hours to re-instate and get the correct falls again. Link to comment Share on other sites More sharing options...
Temp Posted November 28, 2019 Share Posted November 28, 2019 Thinking back to my physics O-level... Concrete has about 2-2.4 times the density of water so 200mm of EPS could float even with 85-100mm of concrete on top. Link to comment Share on other sites More sharing options...
BotusBuild Posted November 29, 2019 Share Posted November 29, 2019 I like simple solutions ? How about leaving out one side piece of the insulation to let any water flow away naturally? Then put it back in place in when you are ready to perform the concrete pour. 1 Link to comment Share on other sites More sharing options...
joe90 Posted November 29, 2019 Share Posted November 29, 2019 On 27/11/2019 at 19:27, MikeSharp01 said: On our build for the garden room I created two holes in the DPM, at the lowest points, to let the water out into the land drain and then sealed them up very carefully with some fearsome double sided mastic tape before we put the concrete in with full BC approval. We didn't need it for the main build as it didn't rain in the final weeks and we had a deep pocket we could pump out and then bale. This sounds good! Link to comment Share on other sites More sharing options...
jack Posted November 29, 2019 Share Posted November 29, 2019 On 27/11/2019 at 16:21, Red Kite said: Concrete for the slab in Jan will probably be OK unless it gets really cold - and slabs are usually not too bad as they are a large volume sat on insulation so they dont suffer from frost damage as they set - but check with your concrete supplier. We had severe problems with our insulated slab pour, which was done on a very cold day. The top layer never really went off properly, powerfloating didn't work properly for the most part, and we eventually had spalling over most of the surface. There may have been other factors at work (eg, the concrete mix), but I'd personally be very careful about pouring if freezing conditions are expected. Link to comment Share on other sites More sharing options...
LA3222 Posted February 28, 2020 Author Share Posted February 28, 2020 Bit of a thread resurrection! Things have moved a lot slower than I anticipated, the insulation is all assembled after some trials and tribulations. Intended to get the dpm nipped today, I got as far as cutting and positioning it all before the heavens opened. Tried to towel dry and stick an edge as me and the missus shuffled along, gave it up as a bad job. Now have a good layer of water in there and a puddle pump arriving tomorrow! Hoping for a dry spell tomorrow so I can get the DPM taped up, have a feeling I'm gonna have to pull it all off to dry any water that got under the overlaps, will be interesting with the forecast strong winds. A dark sense of humour is essential with this self building malarky?♂️ Link to comment Share on other sites More sharing options...
SuperJohnG Posted March 2, 2020 Share Posted March 2, 2020 Fingers crossed for you @LA3222 . Albeit a pain for you it's very helpful for me as I am hoping to do my own just like you but in 6-8 months, so understanding the downsides or things to look out for is very helpful. Link to comment Share on other sites More sharing options...
LA3222 Posted March 2, 2020 Author Share Posted March 2, 2020 11 minutes ago, SuperJohnG said: Fingers crossed for you @LA3222 . Albeit a pain for you it's very helpful for me as I am hoping to do my own just like you but in 6-8 months, so understanding the downsides or things to look out for is very helpful. It's been a challenge so far, with many mistakes made. There are other factors too such as the shape of my slab and the horrendous weather, once I cross the finish line I will post a summary on here which will hopefully be of use to those who tackle it themselves in future. 1 Link to comment Share on other sites More sharing options...
LA3222 Posted March 2, 2020 Author Share Posted March 2, 2020 When the dpm took flight like a sail due to a particularly savage gust of wind it was a low point. Back in the fight now though! 1 Link to comment Share on other sites More sharing options...
SuperJohnG Posted March 2, 2020 Share Posted March 2, 2020 6 minutes ago, LA3222 said: When the dpm took flight like a sail due to a particularly savage gust of wind it was a low point. Back in the fight now though! @LA3222 I imagine a number of expletives were used at that very moment. ? Link to comment Share on other sites More sharing options...
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