Cavity & External Wall Insulation

Yes, those two actions will be a huge improvement. Basic attic insulation is is easy if the attic is accessible. And pumping the wall cavity is a very quick job, maybe 1 day, is not too expensive and when we did ours, the next day there was a noticeable increase in temperature in the house.

Attic is the number 1 first one to get done right. Max out insulation there if you can.

In order to get the wall cavity pumped you'll have to prove there is ventilation in each room it's the only way to get the seai grant so the walls will most likely have to be core drilled with basic pipe ventilation through and through.

For me, I would personal upgrade attic to the best I can. And them concentrate on Windows and doors. Airflow is a major contributor to cold. People often have walls pumped and their windows and doors.are pretty shite condition or really poorly installed leaving gaps around frames and under sills or rubbers on window and door closures are perished or poorly fitted.

I'd put cavity and EWI as number 3 and 4 concerns.

You need ventilation anyway. If your rooms have none then it's quite a bad thing. Cavity pumped or not all spaces need some form of ventilation.

Hi all.

just came across this and found it very useful. It answered a question I’ve been trying to find the answer to. I’m considering putting external insulation onto my detached home. Two sides are cavity block and the other two are cavity walls with brick on the outside. I was wondering if I needed to fill the cavity as well as do the external insulation and seems like the answer is yes due to the heat loss in the ventilated cavity. I just had few further questions which hopefully somebody would have an opinion on:

1. How exactly is the cavity ventilated. Perhaps through the top. I’ve definitely felt cold air coming into certain places at ground level in the house in rooms on the cavity sides particularly the utility room
2. I assume it is still ok to fill the cavity even if there is no insulation whatsoever there? I think this is the case in my walls but I need to scope them
3. Finally. Would it make sense to also cap off the top of the cavity (if this is even possible) to help prevent any residual heat loss even after the cavity is filled.

Any thanks

Tom

Thanks for the response. Much appreciated!

Retro trickle vents. No not for me.

I'd go with wall vents more options to control the airflow with them.

Core drill sleave and covers both sides. You can then put demand controlled systems in when you want or need.

You can't get SEAI work done without ventilation. And I wouldn't let anyone do work without them recommending it either.

Personally I'd go with the latter. The former has high cost and will still need smart ventilation humidity controlled for a good outcome.

Tnx for tips. Had not considered cMEV. Heat recovery ventilation also looking interesting and might offset the cost of running the fan. I'll figure out the ducting routes to kitchen and lower floor rooms and do some basic insulation myself first then likely get an airtightness test done and see where I stand. Probably no harm ordering the new windows with trickle vents eitherway

cMEV is not MVHR and not nearly as expensive either.

Bought a house with a cavity block wall where i do not have the room to do EWI, and tbh I am getting put right off IWI. Not sure I've seen any good stories, and even haven seen cold bridging spots in houses has put me off.

So i am wondering if insulating the crap out of the attic, under the floors, new windows and doors, stoves for fireplaces and sealing all drafts can give me a nice toasty house?

I would massively appreciate any thoughts

Gid, I'm thinking of pulling out.

I actually love the house but wanted to be able to do wraparound or blow in. The inside is finished very well, need to move in straight away, and hate the disruption that internal will bring.