Foundations improvement

[jpinthehouse]

Hi

This is what I have as  proposed foundation's, looking for improvement reduce thermal bridging.

Would it be feasible to keep slab inside block wall and use marmox or similar in line with slab then one block above to sit timber frame on.

Hope this makes sense.

Thanks

John

[MikeSharp01]

Hi. Image is a bit out of focus so struggle to read the item number text to review build up. 

 

Ahhh - it works on a large screen can just read it on my 32" monitor but not on tablet. You are right the block that the frame sits on is the cold bridge along with the cavity tray which transfers the heat to the block from the outside.

Edited November 19, 2017 by MikeSharp01
Found I could read text on large monitor and was able to comment.

[dimpsy]

Always a good one to use,which a few people on here might have possibly copied.

https://www.greenbuildingstore.co.uk/golcar-passivhaus-ground-floor-foundations/

[PeterW]

We built our cavity with a full full below ground of 125mm EPS with 25mm or dry mortar on the outside to hold it in place (150mm cavity) 

 

This then has a full stepped DPC across the inner and outer skin to allow the blown bead over the top - BCO had never seen it before and other than having to do a bit of cavity cleaning due to snots it’s worked really well as it means the edge of the slab is insulated well below ground level. 

[joe90]

I built our founds as per the Golcar site above, no thermal bridging, the only thing we did differently was put two DPC,S, the one on the Golcar site gives a slip plane on the inner skin above the skirting board and my builder had done this once and the customer ended up with cracks in the plaster at this line which needed constant repair. We lowered the DPC to ground floor level ( inside) but this meant the DPC was below ground level outside, so he installed a second DPC in the brick outer skin level level with the internal floor level, 6inches above ground outside. Because we have a French drain around the outside the weep vents from the lower DPC empties into the French drain. My builder did this on another house in the area several years ago and it works very well.

[jpinthehouse]

Thanks for the replies,am I right in thinking that if I insulate below ground in my 50mm cavity then do the dpc s as per drawing this will reduce thermal bridging and be accepted by bco

John

[joe90]

My insulation below DPC was allowed by my BCO but they are all different and apply rules as they see fit, my insulation is as per Golcar which has fairly high compressive strength to stop ground pressures pushing inner and outer walls together. Best to speak to the BCO to get his take on it. I was lucky, my BCO is forward thinking and likes new products and ideas, many BCO,s do not!!!!

[dimpsy]

Maybe of interest.

http://www.touchwoodhomes.co.uk/index.php/foundation-systems/53-strip-foundations

[PeterW]

6 hours ago, joe90 said:

My insulation below DPC was allowed by my BCO but they are all different and apply rules as they see fit, my insulation is as per Golcar which has fairly high compressive strength to stop ground pressures pushing inner and outer walls together. Best to speak to the BCO to get his take on it. I was lucky, my BCO is forward thinking and likes new products and ideas, many BCO,s do not!!!!

 

2 hours ago, dimpsy said:

Maybe of interest.

http://www.touchwoodhomes.co.uk/index.php/foundation-systems/53-strip-foundations

 

Thats about the same as we did although it’s 125mm EPS below ground. I would have gone the Touchwood style route but basically we had to use reclaimed external bricks and they were +/- 10mm on every dimension so the inner cavity vairies substantially ...! One of the reasons we also went blown EPS bead for the cavity insulation. 

[joe90]

Our cavity is 200mm, extruded poly below DPC and rock wall batts above. Our bricks are “tumbled” so to quote our bricklayer they are “ all over the place” but the effect is stunning. My mrs was not convinced brick would look nice but it’s the dogs doodads ( in our opinion, and everyone else that’s seen it).