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How to finish exterior around timber frame build?


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After much procrastination, I'm finally getting round to locking the landscaping details for our build.

 

First some notes on the construction - we have an open box basement (waterproof concrete) wrapped in EPS with a MBC house on the top and where we have doors or full length windows we cast 100mm wide corbels to allow these elements to sit within the insulated portion of the wall.  Doors sit on timber packers off the soleplate to bring them to the required floor level - I should have put lead flashing under the sliders before fitting them to further protect the wood, was able to do this for the front door.

 

Basement acts as DPC, MBC also laid a DPM under their soleplate which comes up over the external EPS leaf.

 

There are 1m stone cobbles backfilling the basement wall with a land drain at the bottom, so very free draining.

 

BC / SE originally required 150mm of the basement wall to be exposed above ground level to act as effective DPC - we then agreed that where this was not possible, ground could be higher than this provided we had ACOs to prevent any water collecting. 

 

Parex render system on the exterior and it must remain 100mm away from ground level to prevent splashes soaking up through the bottom of the render board.

 

Original plan was to dress exposed EPS with UVPC and then backfill and pave such that the slabs were 100mm under the render and tight to the wall, using ACOs where needed for drainage.

 

This is quite low wrt surrounding ground level and would mean a step up to the sliders, so the contractor has proposed an alternative plan where the pavers are at the same level as the end of the render but sit 100mm away from it and we have a french drain all around the perimeter, giving the necessary 100mm clearance from the render system. The paving would actually have a slight fall away from the house.

 

For the doors, the paving would sit in a recess in the base of the sliders and the paving fall away from the house - potentially we could consider an ACO here but would like to avoid if possible.

 

BC and render contractor are happy with this arrangement but I want to double check that there is no risk to the timber soleplate etc with this plan.

 

Am I OK just dressing the DPM down against the wall or should I just trim it off where it pokes over the EPS? I'd bring the DPM up behind the paver and trim, not under like in the photo below.

 

 

Unfinished exterior wall.jpeg

Unfinished sliding door.jpeg

Finished exterior wall.jpeg

Finished sliding door.jpeg

IMG_0891.JPG

IMG_0892.JPG

IMG_0893.JPG

IMG_0894.JPG

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I had this same sort of problem and we used a metal trim to cover the EPS on the first proposal - got it made up especially and wasn't to ££, will add a picture when I get home.

 

We have more of an issue that you through as our finished wall was vitually flush with the edge of the EPS, but it looks nicer that just a black DPC which looks like you are proposing.  People have also wondered about furry animals burrowing into the EPS that is above ground, not sure how mush of a risk that really is though.

 

The second proposal with the doors, be worried water will get down, yes pavers slope away but what about driven ran or water running down the door?

Edited by Calvinmiddle
inability to spell
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That looks smart. If we bring our paving level, with the bottom of the render then the EPS wont be on show really but I may need something to protect the top 100mm,

 

I think I will need to run the dpm over the top of the pavers and cut flush to the door trim and then put a bead of mastic between the paver and the underside of the door trim to make it watertight.

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We did something similar, with a 200mm wide black uPVC fascia trim, fitted over the exposed EPS, with the DPM just dressed down behind it.  Below that I covered the EPS with galvanised expanded metal, and have coarse stone over that all around.  It seems pretty rodent-proof, as I had a pile of left over larch stacked against it for around 6 months or so, and mice made a nest in that but didn't touch the EPS, or even attempt to burrow through the stone.

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See pick, sole plate is above ground, at the top of the first corner

You can see my issue that the frame sits on the slab leaving 100mm of EPS to somehow cover so water running down walls can't track to sole plate.

TBH it's not a great detail, if doing it again I would have added some insulation externally as well to ensure sole plate is kept warm.

But doing that may erode the cost benefit of not have the twin wall which solves the issue by having the internal time we being the load bearing one and then means the outside one hangs over the EPS and so means the sole plate is insulated

image.jpg

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15 hours ago, Calvinmiddle said:

 

You can see my issue that the frame sits on the slab leaving 100mm of EPS to somehow cover so water running down walls can't track to sole plate.

 

 

This is the same detail I have on my PH slab. I put 50mm Rockwool EWI between battens then counterbattened and at the base put Bluclad cement board covered with brick slips.

 

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  • 4 weeks later...
5 hours ago, pocster said:

Hey!

 

Can I ask; what is your timber frame sole plate sat on? - can't be straight on the slab can it???

It could be straight on the slab, but I asked for it to sit on a DPC which is folded up the outside and then covered with the membrane which is on the outside of the OSB racking.

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1 hour ago, pocster said:

Ok

so your sole plate is above damp course for external leaf ?

just checking as I have issues 

I don't have a conventional external leaf. The DPM lines the interior of the Insulation so in theory the concrete slab should never be damp. I tend to over-engineer things so thought if the slab did get wet then the timber I-beam sole plate could be isolated from the damp slab by fitting the DPC.

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