Author Topic: Cavity Wall Insulation Below DPC  (Read 5638 times)

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PSE

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Cavity Wall Insulation Below DPC
« on: March 14, 2017, 02:43:12 am »
My property passed Planning Approval on 7th December 2011. 
The building on my property started in October 2013.

I've just found out that my property has no cavity wall insulation fitted at all below the DPC height.
The builder Bellway Homes) claim that according to their drawings it shouldn't have been fitted even though according to the Building Regulations 2010 it states that the cavity wall insulation below DPC height should continue 150mm below the floor insulation height. 
The builder states that my property would be under the 2006 Building Regulations and not the 2010. 
The NHBC Standards 2013 states in Chapter 5.1 D14:

Quote
(c) cold bridging
The design should ensure that any risk of cold bridging is minimised, giving particular attention to junctions between floor and external walls.
Precautions include:
• extending cavity insulation below floor slab level
• linking floor and wall insulation
• providing perimeter insulation to floors
• facing supporting substructure with insulation.
Any help or advice will be gratefully received.



New Home Expert

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Re: Cavity Wall Insulation Below DPC
« Reply #1 on: March 14, 2017, 09:04:41 am »
In my opinion insulation below dpc level should be above ground level (and the cavity fill) so the insulation cannot act as a wick for moisture.

In addition , blown fibre insulation in at this level runs the risk of drilling through the gas barrier you have. The common solution is to have insulation on the inside of the wall from structural floor level to behind the skirtings. And plasterboard (depending on thickness. This would stop cold bridging.
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Bri

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Re: Cavity Wall Insulation Below DPC
« Reply #2 on: September 14, 2020, 03:13:01 pm »
There is a gap under my skirting board on each side of the front door, slugs slide out from the skirting board.  I stuck a camera in, these is a gap leading straight to the foundations. I can`t see any insulation, the block does not seem to have any mortar with a big bit of DPC sticking out.
Excuse the poor quality picture.

New Home Expert

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Re: Cavity Wall Insulation Below DPC
« Reply #3 on: September 21, 2020, 10:38:26 am »
A case of "what the buyer can't see" here.
Yes the block joints should be filled with mortar. The protruding DPC if on the inside wall may cause water in the cavity to come inside. Whatever side of the wall the dpc is on, it could be mis-located meaning some of the bed joint (the amount sticking out) is not damp proofed.

This needs addressing, as slugs should not be able to get in and insects etc will too.
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Bri

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Re: Cavity Wall Insulation Below DPC
« Reply #4 on: September 29, 2020, 11:42:28 pm »
I've mentioned this to the developer several times without any reply to my question.
Slugs, woodlice and beetles all come in from this area. As in my other post, there is a DPC fitted high up on the house that breaks the expansion joints even though the expansion joints are all wrong.  I would guess my cavity wall is full of debris too.
When they remove the blocks to take out this DPC I'll shine a torch down and look.
The MD will not come out to see me even though I've escalated these faults many times.