External Insulation

PaulDolan

Hi All,
I am renovating approx 1960s Bungalow and adding a small extension out the back. 110sqm total.
The construction is cavity wall (50mm Cavity) to the top of the windows- then there is a large ring beam around the whole house which bridges the cavity from the top of the windows up to the roof plate (500mm).
I am replacing all windows
I have dug out old floors and will be fitting dpm/radon barrier to insulated screeded floors.
I have talked with some different builders and been given different opinions:
1. To dryline the external walls taking 75mm of space out of each room
2. Pump Cavity and everything'll be fine (cheap)
3. Exteranlly insulate the house (expensive) 140 sq m

The problem I have with 1. is that there would be thermal bridging where an internal wall joins the external wall. Space wise I cannot afford to lose more by drylining internal walls as well.

The problem with 2. is that it is only a 50mm cavity and pumping the cavity may not insulate the house enough & the problem of the ring beam.

The problem with 3 is expense. i have seen prices of €100 sq m.


What are peoples realworld experiences of external insulation?
Have the prices come down?

Thanks

BryanF

1. yes thermal bridging & interstitial + if your changing the windows its a good time to consider these details carefully.. whatever option you choose - look around this site at the amount of people with condensation issues on one hand and drafts on the other - so consider the air-tightness & ventilation strategy carefully
2. pumping is a start, but why not tell us more about what other work you plan to do, and what actual retro-fitting standard your aiming for passive or building regs and what amount of running costs would you like or comfort would you expect. what budget have you set yourself, you could do this and easily not have change from 50-150g:eek::)
3. ring beam an for a host of other reasons ewi I'd go external, but here's the problem, you rate 100sqm expensive, and the cheaper side of the quotes you may get, will not have the back-up of the system manufacturer or offer you the products you'll need for the performance or lifespan.

best of luck - consider getting an arch in to spec the details, specification, expected kwh/m2/yr for heating loads etc

Spread

You can go with internal insulation and not have to do the inner walls. But it's a bit on the dusty side. Just cut away 1" (plus the thickness of the insulation and backing) of the internal wall at the T point. Insulate the outer walls. Stud out and slab or blob the void. Skim or mud and tape all.

S Connor

PaulDolan wrote: »

Hi All,
I am renovating approx 1960s Bungalow and adding a small extension out the back. 110sqm total.

What are peoples realworld experiences of external insulation?
Have the prices come down?

Thanks

Hi. I had external insulation put on my home almost 2 years ago and I find the difference is amazing. My house was built in the 60s and was freezing cold and quite damp as it had no insulation whatsoever. I had 120mm insulation installed on all external walls and we insulated the attic ourselves with 100mm polystyrene at the same time. Previously we would have had our heating on for 13 to 14 hours a day and would still be complaining of the cold. Now we don't even have it on the timer as we find we can't stand the heat after an hour or so!!! It's unreal!! The house also holds the heat for much longer whereas before being insulated it got cold as soon as we turned off the gas boiler.

Unfortunately, along with the good I also have to tell you the bad. As I have said in previous threads we had a horrific and very stressful experience with the first company we used to install external insulation. It was so badly installed that we had to hire a chartered surveyor to examine it. He was completely shocked by the standard of the work and the condition my home was left in. He took photos that show work so badly done they have to be seen to be believed!!! We had to get the insulation totally redone, by another company, at huge expense to ouselves of course!!!! However, I would still recommend external insulation providing you do some very very careful research of your contractor first.

Hope this helps.

BryanF

Spread wrote: »

You can go with internal insulation and not have to do the inner walls. But it's a bit on the dusty side. Just cut away 1" (plus the thickness of the insulation and backing) of the internal wall at the T point. Insulate the outer walls. Stud out and slab or blob the void. Skim or mud and tape all.

the general nature of Irish 60's construction methods mean that drylining any substantial internal insulation would require a hygrothermic check and the amount of thermal bridges that remain with dry-lining, mean there will still be a larger amount of heat loss than with EWI.

Spread

BryanF wrote: »

the general nature of Irish 60's construction methods mean that drylining any substantial internal insulation would require a hygrothermic check and the amount of thermal bridges that remain with dry-lining, mean there will still be a larger amount of heat loss than with EWI.

I'm talking empirical evidence here. Did this with a cottage 15 years ago. Still stay there for holidays. Being from the old school, I rely on tried and trusted ways. It's not rocket science. There is a lot of hogwash written by people/firms with agendas.

Stove Fan

We bought a total wreck and gutted everything and so I drylined my 1950's block detatched 105sqm bungalow using 50mm kingspan slabs on all outer walls and inner walls except in the inner walls of the hall and bedrooms where I used aeroboard slabs about 38mm thick, fixed using the mushrooms. The suspended wood floors have 8 inches of rockwool insulation between the joists.

This has made the house very warm but if I was doing it again I would of done the ceilings as well. The bedrooms have hardboard ceilings. The loft only has about 8 inches of earthwool insulation:rolleyes:.

If we were staying I would kingspan the bedroom ceilings eventually as well as topping up the loft insulation.

We heat our home with a medium sized 8kw boiler stove and it makes the place lovely and warm:) Villager Berkley 26,000btu integral boiler.

It's pretty good but you can't have too much insulation:D If the outside condition is poor EWI would be ideal as you get the insulation and a new exterior finish.


Stove Fan:)

BryanF

Spread wrote: »

I'm talking empirical evidence here. Did this with a cottage 15 years ago. Still stay there for holidays. Being from the old school, I rely on tried and trusted ways. It's not rocket science. There is a lot of hogwash written by people/firms with agendas.

there's no agenda here. i wonder would you feel the same if you were heating this house all year round and paying current energy costs of home heating..

Spread

Double post

Spread

Hey BrianF! I recognise that you are giving an unbiased opinion here. And your posts are very informative. Lots of books/leaflets/mags have been written about the various/best ways of insulating. Lots of these give great credence to lab tests. However, because of the vagaries of buildings, you cannot (cost wise) get everything to match. So a little common sense is called for. Nit picking/angels dancing on pinheads is the forte of some professionals who have a vested interest. All most people want is a warm house at the best price and the most cost effective for heating.
I'd honestly say that if I lived in the cottage for twelve months of the year that my heating bill would be pretty low. I chucked out the rads, boiler and back boiler ........ vented fireplace on the outside and blocked it up ...... put point of use water heaters in for handbasins ....... electric power shower ...... and heated panels on the walls. Thermostatically controlled these work out at about 22c per hour and when doors and windows are closed, you can turn them off after 20 mins. The dry-lining method (on 9:3:1 rendered walls) was 2X1s steel nailed on at 25" centres, 1" aeroboard inserted between, then 8'X4' X 1.5" rigid insulation board (forget the name, blue in colour) screwed long length horizontal to floor, Same boards screwed to ceiling, walls then sheetrocked followed by ceiling. The lot then skimmed.
Double glazed teak windows with reveels and soffits insulated (walls are 22" thick) plus draught excluders on all doors make this place toasty at the right price.
I lived there full time from November to March last year and although I forget the electric bill, found it very cheap - considering the weather.

Mountain Rescue

Im about to start the same job as paul,he has described my house down to a tee.I have decided on external insulation,im thinking Kingspan kool therm,im also thinking about changing my windows and moving them to the outside of the external block,i hear this prevents thermal bridging??,im also thinking about dropping the external insulation below ground level,again to prevent thermal bridging??, Roof will be replaced and insulated,my problem now is ventilation in the house,iv seen to types of heat recovery systems,the stanard system with a unit in the attic pumping all the rooms,the second system is a heat recovery unit built in to the external wall,similar to the vents we have in bathrooms,has anybody any tips or ideas for me on any of the above,

Thanx

BryanF

yes this can prevent thermal bridging, its about how the overlap with the insulation is managed + the air-tightness membrane/seal

yes, the overlap at ground level can be demonstrated using a thermal modelling program. its an alternative to digging and installing more insulation under the floors by extended insulation externally to the footings. the overlap with wall insulation and details at roof level should also be carefully considered.

achieving the air-tightness required for MVHR in an existing building can prove difficult without professional involvement and a lot of detailing, see here regarding How-do-demand-control-ventilation-and-HRV-compare

jrby

Paul,

I got my house externally insulated....partly for the insulation but more so becuase the house was externally plastered very poorly and we would have had to strip it all back and re plaster the entire outside of the house one way or the other.

If you are looking to compare prices for the options you are looking at, I would make sure that you include in options 1 and 2, the cost of making your house presentable on the outside....or alternatively deduct it from option 3......

There are a good few chancers out there in the industry. I would receommden that if you go with option , that you get a few differtn quotes in and make sure they are laid out line by line as to what you are paying for. We got some very low priced quotes in (with little or no detail)and some much higher but more detailed quotes in. when we went back to the cheaper quotes in and asked them whether they were including this or that....we found out that a lot of stuff was left out.

the other thing to check is the measurements......when we asked what the measurements of our house was from the people that quoted us, it varied by as much as 50%....that shouldn't be rocket science.

The person we gave the job to, spent an hour measuring our house, gave us a quote which had a about 30 - 40 different line items....giving a detaiiled breakdown of labor and materials for each element. He was one of the highest in terms of cost but didn't vary from his price.

Let ke know if you have any more questions.

marknjb

one thing i dont like about the external stuff is that the skim coat they cover it is very light i would hate to see a young lad hurling a ball against it

Mountain Rescue

hi Paul how much did it cost you to dig your floors out.iv the same size house 110meters squared aswell.

martin6651

I'm thinking of getting ext. insulation but heard from a friend that the installer told him not to lean a bike against the wall. Can the wall be that easily damaged.

Smithers1

jrby wrote: »

Paul,

I got my house externally insulated....partly for the insulation but more so becuase the house was externally plastered very poorly and we would have had to strip it all back and re plaster the entire outside of the house one way or the other.

If you are looking to compare prices for the options you are looking at, I would make sure that you include in options 1 and 2, the cost of making your house presentable on the outside....or alternatively deduct it from option 3......

There are a good few chancers out there in the industry. I would receommden that if you go with option , that you get a few differtn quotes in and make sure they are laid out line by line as to what you are paying for. We got some very low priced quotes in (with little or no detail)and some much higher but more detailed quotes in. when we went back to the cheaper quotes in and asked them whether they were including this or that....we found out that a lot of stuff was left out.

the other thing to check is the measurements......when we asked what the measurements of our house was from the people that quoted us, it varied by as much as 50%....that shouldn't be rocket science.

The person we gave the job to, spent an hour measuring our house, gave us a quote which had a about 30 - 40 different line items....giving a detaiiled breakdown of labor and materials for each element. He was one of the highest in terms of cost but didn't vary from his price.

Let ke know if you have any more questions.

like to share the name of the co. you opted for in the end?

jrby

Here's the website, Peter Sullvan is in charge and his mobile is 0862426967.

http://hwi.ie/about

if you want to call over to see our house you can PM me.

khpuddin

Would you be able to PM me the name of the company you went with if you were happy with them?

jrby

Here's the website, Peter Sullvan is in charge and his mobile is 0862426967.

http://hwi.ie/about

khpuddin

Thanks Jrby the website seems to be down but I will give Peter a call

If anyone else has any recommendations or warnings it would be great if you could send them on!

Montgomery287

Has anyone got experience (experience) of external insulation on solid walls?

manana

Is it ok to just externally insulate the back of the house only?