Airtight house

mendel

moving along with renovating 2 storey dwelling. We want to airtight the house.

Have to get engineer advice re the foundation floor level

thinking of interior plasterboard, insulation at rafter level and attic level, triple glazing windows.

Is this going to achieve airtightness? at the above level, would we need HRV unit?

justflow1983

Are you going to insulate the internal walls or just put plasterboard on them? I wouldn't waste money on triple glazed windows if the rest of the building isn't well insulated.

Houses are generally not made hermetically airtight, but what we try to do is minimize the amount of air infiltration as much as possible (in the case of a passiv haus its very tight) using tapes, membranes, and other seals. At a certain level of airtightness, you need an HRV to make sure you have fresh air coming in, since you won't have fresh air working its way through the building fabric. Your airtightness strategy will be closely linked to your insulation strategy since sometimes the same piece does both.

If you post more information about the place you're renovating you'll get more specific responses and strategies that will help you out.

MicktheMan

Mendel,
your query is way too vague for a definitive answer.

You first need to figure out where you airtightness boundaries are (for instance, will it be the pitched roof section or the flat ceiling). Then you need to figure out how best to make each element airtight and how you will seal between elements (e.g. roof to walls, walls to floor, windows to walls..).

You will need to "educate" all trades on site about your airtightness ambitions and ensure they do not compromise the air tightness work done.

Generally if you achieve an air permeability result of 5m3/hr/m2 @50Pa or better you could consider using a hrv system to ventilate the space.

mendel

thanks for the replies.

I understand your point about the attic/pitch roof (after having to re read numerous times) insulate to the attic floor i reckon, whats the point in letting heat escape to the attic??

the house is about 30 years old, cavity block construction, the cavity was pumped with insulation although we reckon it to be patchy. the ground floor floor (foundation concrete??) is also not complete and will at a minimum need to be levelled.

I dont think we can afford external wall insulation. Therefore thought best thing insulate the interior walls and then do thermal test?? (is that what its called) to see where heat would escape and then try and fill in the cavity insulation.

We were also advised to tape all the windows

so questions are

1. what is the best method of insulating the internal walls and
2. how to proceed with the ground floor

Am i missing loads?

I appreciate I'm very green about this (excuse the pun)

mark2003

Make sure you get the right builders to do the job.Make sure they are up to date in how to make a house airtight and use the right materials.It is not to hard to insulate a house up to the standard regulations but a total different story to airtight one.Use plenty of foam and tape to seal joints.Get a BER assessor to give you exact details in what you need.Also get an airtightnes test after completion and you will know if you need an hrv unit.Good luck

Wally Runs

We carried out the same exercise in a 1970 9 inch hollow block 4 bed house.

In brief, we (the builder I mean) used membranes, tapes and internal composite insulation boards. As regards the floor, it was suspended timber, but we had UFH put in. In the process of doing this, insulation, screed etc they were made air-tighter. The final number was 2.9 (whatever the units ).

It took a lot of effort on the part of the builder to get to that level and we had to stress time and time again that if they did not meet the target level (5 units) they would have to keep at it until they did. The contract was at a fixed cost.

The builder got great advice and support from the materials supplier, who came out several times to check and advise as regards zones and problem areas. they even provided a days free course. This was six months ago, builder has gone on to be an expert in home insulation and HRV (never said thanks). No problems to date.

House went from a G mega minus to B1.

Skatey

Wally Runs wrote: »

The builder got great advice and support from the materials supplier, who came out several times to check and advise as regards zones and problem areas. they even provided a days free course.

That's great to hear. We're in the planning stages at the moment and are making the house as airtight as possible. I think I would benefit from using a supplier who would educate us too. Could you possibly send me a PM with their name, please? Many thanks!

ThinkGreen

PM details here too please

tp25

Wally Runs wrote: »

We carried out the same exercise in a 1970 9 inch hollow block 4 bed house.

In brief, we (the builder I mean) used membranes, tapes and internal composite insulation boards. As regards the floor, it was suspended timber, but we had UFH put in. In the process of doing this, insulation, screed etc they were made air-tighter. The final number was 2.9 (whatever the units ).

It took a lot of effort on the part of the builder to get to that level and we had to stress time and time again that if they did not meet the target level (5 units) they would have to keep at it until they did. The contract was at a fixed cost.

The builder got great advice and support from the materials supplier, who came out several times to check and advise as regards zones and problem areas. they even provided a days free course. This was six months ago, builder has gone on to be an expert in home insulation and HRV (never said thanks). No problems to date.

House went from a G mega minus to B1.

PM details here too please

muffler

tp25 wrote: »

PM details here too please

Stop being lazy and send a PM yourself.

Thread closed.