External Insulation On Top Of Internal Insulation

FunkyDa2

Hi all,

Our house is a 64 year old semi d, with solid (9 inch on the flat) external walls plastered internally, and pebble dashed externally. We moved in 33 years ago, and within a few years I drylined to a thickness of 1 and 3/8 inch, using wood battens, polystyrene panels, plastic vapour barrier, and 8 foot by 4 foot plasterboard sheets.

I managed to get the downstairs front room, the hall and stairwell, the front bedroom, and the "box" room completed. I never got the back bedroom done, and I baulked at doing the bathroom and kitchen because of the amount of work required.

3 years ago, we got the bathroom refurbished by a builder, which involved stripping out the fixtures (with the exception of the hot water boiler and plumbing), insulating the walls to a thickness of 75mm and tiling them, replacing rotten floorboards and installing new fixtures.

My wife says the house is still cold and is looking to get exterior wall insulation installed. She reckons that she couldn't deal with the upheaval of getting the kitchen drylined.

My question is, then, if EWI is installed, should the existing interior drylining be removed to allow the wall to "breathe" properly?

Thanks

PMBC

'64 years' indicates built around 1951-52. Are you sure it was 9 inch solid block? There was a large number of houses built in mass concrete around that time. What kind of heating do you have?

FunkyDa2

My next door neighbour, who is in his 90's, is the original buyer of his house and told me in the past that he came up to the site during construction to check on progress, and saw the blocks being hand made on site. I got replacement windows and doors fitted years ago, and when it came to the sliding patio door replacing the back window, the installers had to make an unplanned rental of a Kango hammer to knock out the blockwork under the window. Twenty years ago, I drilled a 4 inch hole in the bathroom wall to install an extractor fan, and it took me 45 minutes, using a heavy duty rented drill and core(?) bit.

I have a linked open fire with high output back boiler, and oil fired central heating system. When the open fire is not in use (which is most of the time), I remove the grate assembly and put a decorative panel with sponge rubber seals over the opening. I have a few small holes in the panel to allow controlled airflow up the chimney.

Calahonda52

before u delve into the ewi project you need to address uncontrolled ventilation in the house as this is the source of the heat loss.

Okay you have addressed the chimney issue for ventilation but what about uncontrolled ventilation and floors, windows, doors, letterbox, wall vents, attic hatches, etc.

When u dry lined the walls, how did you deal with the wall floor connection from an airtightness perspective?

How did you deal with perforations in the plastic for sockets, switches, pipes etc

Then how well insulated is the attic?

If the ewi is breathable, then you don't have a problem?

How will they deal with the pebble dash from a continuity perspective.

My hunch is that, given the age of the house, the construct, the work done, your age etc, that the 20k that the ewi will cost might be better spent making the house more airtight from a controlled ventilation perspective.

Keep warm!

Metric Tensor

Completely agree with Calahonda.

When the cold windy weather comes back (probably next week knowing Ireland) run your hand over all the internal joints, corners, window sills, etc. in the house and in a house that age you'll probably be able to feel the draughts by hand. Your heat is going out these gaps.

Unfortunately it's a tricky thing to fix because it means a lot of little bitty details. Well worth it if you can though!

BryanF

FunkyDa2 wrote: »

Hi all,



My wife says the house is still cold and is looking to get exterior wall insulation installed.

My question is, then, if EWI is installed, should the existing interior drylining be removed to allow the wall to "breathe" properly?

Thanks

Ewi should be ok. Is it possible for you to check/open up the dry-lining? maybe behind some furniture ideally in the coldest (dampest) room

I'd be more concerned that it's done correctly: down to foundation, overlap at eaves, wrapped around windows, chimney, gutters,downpipe, satellite, alarm - half the country has really poor jobs done. Re air-tightness I concur with comments above