Cavity & External Wall Insulation

witnessrenegade

Hi,

Bought our home (Built in 1971) this year with a BER of F

No attic or wall insulation in the house

I will get attic insulation done shortly, and I was wondering what to do regarding wall insulation?

Is it best practice to get both cavity insulation and external wall insulation, or just one?

With our budget, we wouldn't be able to get external insulation at the moment, so is it best to get cavity insulation done for the time being while we save?

Also, I have noticed on cold nights we get quite a bit of condensation in upstairs rooms, with no wall vents upstairs, should these be installed to prevent damp? The UPVC windows in the house are about 20 years old so they don't have trickle vents installed to provide fresh air.

Thanks

Biker1

Yes it is best practice to pump the cavity if external wall insulation is being done.

As there is no insulation anywhere then you will get condensation on the walls and ceiling. You need to deal with the insulation and airtightness first before addressing the ventilation.

Boardnashea

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.

tom1ie

https://www.boards.ie/discussion/comment/121460716#Comment_121460716

Hi boardnashea, we are thinking of getting this done also- what sort of price did you pay if you don’t mind me asking and was the finish where they drilled the holes in the outside walls noticeable after?

Did the whole process take long?

listermint

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.

Boardnashea

https://www.boards.ie/discussion/comment/121460733#Comment_121460733

Hi Tom

I don't remember the price and it was 20 years ago so I'm sure it has changed "a bit" since! The finish was good. They matched the existing finish quite well. We were pebble dash at the time so, i guess that made it easier.

They were finished in a day or less, single storey detached, about 1000 ft2.

witnessrenegade

Thanks for all the responses

Will go ahead and get the attic insulated as much as possible for now, and may get the cavity walls insulated in the New Year.

Hallway is quite cold and I think it's from the front door, the external doors were rated Very Poor on BER, while windows were rated Fair. We want to update both, so might bring forward replacing the doors and do it sooner than we expected to in order to improve the warmth in the house.

Thanks again

com7

Hi

I m considering getting the wall cavity pumped ...we ve changed the windows this year but I was told they ll need to put ventilation into each room , the coldest room would be a bedroom at the back ( attic is done by the way ) I m wondering is it worth it if i m going to have ventilation coming in re does it just defeat the purpose ? has anyone that has this done got any thought s please !

Thanks in advance

listermint

https://www.boards.ie/discussion/comment/121503081#Comment_121503081

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.

MicktheMan

https://www.boards.ie/discussion/comment/121503081#Comment_121503081

There are far better ways these days than the old 'hole in wall' or window trickle method for providing appropriate ventilation.

Might cost a bit more but then cheapest is rarely the best.

tomahawke

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

listermint

It's probably vented from the bottom, slated vents. Or brick vents.

Yes you can fill cavity sans existing insulation it'll just take more material to blow in.

No you don't need to seal the top. The beaded fill should prevent excessive air flow in the space and acts as a barrier for convection or conductive heat transfer.

tomahawke

Thanks for the response. Much appreciated!

onlyonpaper

https://www.boards.ie/discussion/comment/121503387#Comment_121503387

We had triple glazed windows and doors installed about two years ago. Planning to get the external walls pumped in the near future and discussed with local approved company. I was surprised when he said that I will need ventilation in each room and he said doing it in the windows was the simplest method. How extensive is this job. Do the windows have to be taken out. There are 10 windows and what would I expect it to cost approx

listermint

https://www.boards.ie/discussion/comment/121943190#Comment_121943190

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.