What would you do?

[AG_YB]

Ahead of design... I'm looking to gain some insight from those with the experience... 

 

If you were building a masonary build (block and brick) from new.... What wall construction/make up would you choose and why? I'm talking about cavity size, insulation choice (which brand too) and then interior side finish?

 

 

*just to add, supposed you are in the North of England, non coastal region. 

 

 

Edited October 17, 2020 by AG_YB

[PeterW]

External brick, 150mm cavity, medium density block and blown graphite beads. Then line with 25mm PIR between battens and aluminium tape all joints before boarding with standard plasterboard and skim. This gets you decent thermal performance plus the PIR and batten increases this plus provides an air tightness layer that most builders can understand without the use of special membranes. 
 

Brand on PIR is irrelevant - buy what is cheapest locally. Blown beads aren’t a DIY install so just find someone with a decent spec -  we specify Instabead Diamond which is about the best you can get. 

[AG_YB]

Hi PeterW, 

 

Thanks for the quick reply and info. 

 

Forgive me if this is a daft question - if one went this route, would that create an level of airtightness then that MHRV is required?

 

Also just out of interest, why beads over more PIR in the cavity? 

 

Thanks again 

[Alexphd1]

Single block on side with 200mm eps external wall insulation. Purge coat inside of block work for air barrier either batten out or frame wall then plasterboard. This would match very well with a insulated raft foundation and spray insulated roof. It would be one continuous insulated envelope. 

[PeterW]

1 hour ago, AG_YB said:

Hi PeterW, 

 

Thanks for the quick reply and info. 

 

Forgive me if this is a daft question - if one went this route, would that create an level of airtightness then that MHRV is required?

 

Also just out of interest, why beads over more PIR in the cavity? 

 

Thanks again 

Yes it’s airtight enough for MVHR. 
 

And PIR in cavities is horrible to work with and expensive as you need the 1200/400 boards and they need to be fitted properly to work. It needs care and attention at detail areas by the brickies. Beads full full the cavity with no gaps and mean your brickwork and blockwork can go up a lot quicker. 

[epsilonGreedy]

My build will be a variation of @PeterW's suggestion with 100mm cavity, woven cavity batt insulation plus 40mm PIR. If starting again I would opt of 150mm cavity.

 

Hopefully @joe90will be along here to comment. He is very happy with his build, 200mm cavity plus traditional wet plaster finish direct on the inner block wall.

 

I like the idea of the extra intermediate PIR insulation layer because I hope the reduced room facing thermal mass, comprised of just 12mm of plasterboard, will result in a responsive house with a more tunable internal temperature.

[joe90]

Someone call me????.. yes i am very happy with my 200mm cavity full filled. With regard (pppsssstttt thermal mass ?) I hear the argument that just the plasterboard within the house is enough and can not argue as I don’t know (Or understand) all the facts. I do understand @epsilonGreedy reason for extra PIR and plasterboard fir a more responsive house but I hate hollow sounding walls and not being able to hang heavy stuff wherever I want in the house (apart from the couples of stud walls I have upstairs). So it’s horses for courses. I am retired and mostly at home so the house stays above 20’ and so far this year the heating is yet to come on. Everyone comments how warm the house is even with no heating. If I were to go away for two weeks in the middle of winter with the heating off I am sure it would take a fair while to heat up (but I have a wood stove which can chuck the heat out if required). ?

[Oz07]

Have you had any heat input into your house yet @joe90? Wood burner etc ? I've been using heating a couple of hours each night and it doesn't feel as warm in the morning as my last place I built to similar spec. This one has mvhr I can only assume it's not as efficient at retaining heat as advertised or is running too fast. Tbf the thermostat hasn't shown below 16/17 but I've set it to click off at 19 for the heating. 

[joe90]

1 minute ago, Oz07 said:

Have you had any heat input into your house yet @joe90? Wood burner etc

No, well, I did light the woodburner one evening last week as er indoors felt chilly (I was in a t shirt). The heating buffer is up to temp but the house thermostat set to 20’ has yet to call fir heat.

 

some of you may remember my large conservatory on the south side of my build and dire warnings were given Here regarding the overheating that would take place, well it did get a bit hot (a bit like the south of France, but you have to pay to get there ?)on sunny but cool days Like today it’s 25’ and with the bifolds open into the house it warms the house up lovely so I am getting free heat in the shoulder seasons which I had hoped (planned) for?.