Tue, 19 Dec 2023 06:47:30 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276173#Comment_276173 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276173#Comment_276173 Tue, 15 Oct 2019 21:10:36 +0100 Tullich
His amendments would mean the make up is as follows:
250mm compacted sub base
50mm sand blinding
DPM
EPS layers (held back from the slab perimeter to form the ringbeam
DPM
Steel reinforced concrete

I'm struggling to find similar constructions which use the first DPM over the sand blinding. Can anyone shed some light on the accepted method vs his suggestion as above?

Thanks]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276177#Comment_276177 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276177#Comment_276177 Tue, 15 Oct 2019 22:44:57 +0100 djh http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276180#Comment_276180 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276180#Comment_276180 Tue, 15 Oct 2019 23:05:40 +0100 Tullich
I've yet to find out the answer and I can't see that it's really doing anything.

His letter says "1200 gauge dpm below the insulation providing protection from the blinded hardcore layer as per the manufacturers instructions". Neither the architect or SE have drawn a DPM in this location though....]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276185#Comment_276185 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276185#Comment_276185 Wed, 16 Oct 2019 08:42:29 +0100 Peter_in_Hungary Posted By: TullichHis letter says "1200 gauge dpm below the insulation providing protection from the blinded hardcore layer as per the manufacturers instructions". Neither the architect or SE have drawn a DPM in this location though....
The key here is the BCOs get out clause 'as per the manufacturers instructions'. Unless you can find 'manufactures instructions' detailing both then there is no need. DPM specs that i have seen for EPS have either the DPM above OR below the EPS but not both. I could see a need if the below slab insulation was high density rockwool or alike but not with EPS.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276189#Comment_276189 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276189#Comment_276189 Wed, 16 Oct 2019 09:47:33 +0100 PeterStarck Posted By: TullichHis letter says "1200 gauge dpm below the insulation providing protection from the blinded hardcore layer as per the manufacturers instructions". Neither the architect or SE have drawn a DPM in this location though....
We have an Isoquick foundation system on 250mm compacted type1 and 50mm granite fines. The only DPM is between the EPS and the concrete. My BCO accepted the SE specifications. I would ask the BCO why he hasn't accepted the SE details.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276194#Comment_276194 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276194#Comment_276194 Wed, 16 Oct 2019 11:54:10 +0100 djh Posted By: Tullichthe manufacturers instructions
Who is the manufacturer he is referring to?

Rereading your original post, I'm not clear how the ringbeam is insulated? Or what is the construction above it?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276196#Comment_276196 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276196#Comment_276196 Wed, 16 Oct 2019 12:28:07 +0100 Peter_in_Hungary Posted By: djhWho is the manufacturer he is referring to?
Almost certainly no particular manufacturer, just a get out phrase used when he is not sure what exactly to put - doing / demanding what the manufacturer specifies is almost never wrong, even if you don't know what you are talking about!]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276200#Comment_276200 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276200#Comment_276200 Wed, 16 Oct 2019 15:17:57 +0100 djh Posted By: Peter_in_HungaryAlmost certainly no particular manufacturer, just a get out phrase used when he is not sure what exactly to put - doing / demanding what the manufacturer specifies is almost never wrong, even if you don't know what you are talking about!
Well, it's a custom design, so there is no manufacturer AFAIK. And there's no manufacturer's details that require a DPM between a blinding layer and EPS that I'm aware of. In fact, the suggestions I've seen are exactly the opposite - to use a layer of EPS between the DPM and the blinding/hardcore to protect the DPM!

So asking the BCO to be specific seems like a plan to me, and a most curious use by him if he didn't have any manufacturer in mind.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276204#Comment_276204 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276204#Comment_276204 Wed, 16 Oct 2019 17:18:43 +0100 Peter_in_Hungary Posted By: djhso there is no manufacturer AFAIK
There is a manufacturer - of the EPS so the BCO will want the installation recommendations / standards for the EPS followed. IMO ar#e covering by the BCO]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276214#Comment_276214 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16284&Focus=276214#Comment_276214 Thu, 17 Oct 2019 08:30:07 +0100 GreenPaddy
- you are creating a void below the DPM, albeit sheets of EPS put into it, but water "could" make it's way to that point, and may stick around or free drain away, we don't actually know.

- if water gets into that area of EPS, what happens to that insulation both over the short term and the longer term, structurally and insulatively?

- if you are the designer of this system, then you MUST have the answers to these questions. The BSO has every right to ask you to prove your design (that's his job).

In any case, before you can try to answer his question/concern, you need to be clear exactly what his concern is. The warrant responses don't always make it clear, referring more to the specific part of the BRegs in question. It can feel like the BSO is "having a go" at your design, but I think he has every right to make sure your design stands up.

I sometimes get P'd off at the BSO's, when they come back with these sorts of questions, but usually on reflection, I recognise I'm P'd off at myself for not providing proof of the detail's robustness or suitability. When I've done that, it goes passed no problem.

By the way, on my builds, I do put a DPM under the EPS, AND a second one to hold the water in the concrete, and not let it run into the EPS joints, especially if the ground conditions are a bit suspect. That's my call, a little bit of very cheap insurance. I've built plenty of houses this way, and I'm out on site as well as in the office designing, so I see how things can be done on site, and it's not always as the drawings might suggest, so some redundancy can be a good thing.]]>