Air tightness new build - considering MVHR

[Jde00]

Hi,

My new build has a reported tested air tightness of 5.8 m³/h.m²in the EPC. I don't see any obvious sources of draughts other than perhaps the back of toilets which will be addressed shortly. How else can this figure be improved?  I quite like the idea of retrofitting a MVHR system at some point in the future.

 

Cheers!

[Bitpipe]

36 minutes ago, Jde00 said:

Hi,

My new build has a reported tested air tightness of 5.8 m³/h.m²in the EPC. I don't see any obvious sources of draughts other than perhaps the back of toilets which will be addressed shortly. How else can this figure be improved?  I quite like the idea of retrofitting a MVHR system at some point in the future.

 

Cheers!

 

 

What is the house construction method and who built it?

 

If it is traditional block / brick then the gaps are likely between the blocks and at floor / roof junctions, where the joists penetrate etc. Even TF will have lots of gaps.

 

Add in gaps between door and window frames and walls, all intentional penetrations to the exterior (pipes, cables etc). Finally trickle vents in windows, extractor fans, poor seals in windows & doors, keyholes etc.

 

Some of these you can address but many you probably can't.

 

Good airtightness is not expensive but needs to be designed in and attention to detail at every stage of the build.

 

[Jde00]

Yes traditional block and brick. 
so having a current value of 5.8 is it worth exploring improving it?

[nod]

5.8 isn’t very good for a new build 

Though builders only have to test one in seven Which makes a mockery of the testing scheme 

 

A good place to start would be to seal around the bottoms of your skirting boards  As the dry lining is often not sealed correctly 

 

If the boarding is done correctly It’s easy to hit 2 without sealing around floor joists and lofts 

 

 

[Jde00]

Should you seal around spotlights ? My house is full of them. I think I have close yo 100 spotlights. And the ceiling is like a cheese grill. You can clearly feel air coming out of the fittings 

[Iceverge]

 

 

Read this thread. It's much the same situation yours.

[NSS]

15 hours ago, Jde00 said:

My new build has a reported tested air tightness of 5.8 m³/h.m²in the EPC.

 

As mentioned, developers don't have to test every property so that figure may not even be for your home, just one like it. That means that yours could in fact be better or worse. The only way to know is to do a test on it.

[Jde00]

1 hour ago, NSS said:

 

As mentioned, developers don't have to test every property so that figure may not even be for your home, just one like it. That means that yours could in fact be better or worse. The only way to know is to do a test on it.

 

 

It's a small development, with only 4 houses like mine and all 4 have different values for air tightness. However I understand your point and I will be doing one as soon as the builder finishes up some stuff. For example the back of the toilets have not been finsihed by the decorator so there are quite big gaps where air can get through.Lots of mastic left to correct too...

[SteamyTea]

21 hours ago, nod said:

good place to start would be to seal around the bottoms of your skirting boards  As the dry lining is often not sealed correctly 

This may stop the drafts inside, but does very little for the thermal performance.

[nod]

1 hour ago, SteamyTea said:

This may stop the drafts inside, but does very little for the thermal performance.

Very little you can do retrospectively 

[SteamyTea]

16 minutes ago, nod said:

Very little you can do retrospectively

Yes.

Why I think an air test needs to be done as soon as possible in the build.

Probably save the extra 250 quid it costs during the first winter.