External wall insulation is it any good?

[dextadriver]

Firstly we live in a council owned bungalow so it doesn’t really matter what happens but… I want to be able to ask questions about it when they arrive to carry out survey,
A local builder told me it will cause big problems with damp in cavity
Could this be true?
Thanks

 

[JOEPRO]

What is the approx property age?

What is your current existing wall construction would be a good start. (Eg, render external finish, 4 inch outer and inner block leaves and 100mm cavity)

 

[Mark 5]

Firstly we live in a council owned bungalow so it doesn’t really matter what happens but… I want to be able to ask questions about it when they arrive to carry out survey,
A local builder told me it will cause big problems with damp in cavity
Could this be true?
Thanks

Do you mean ' External ' or Cavity Wall?

 

[frank horton]

my friend builds houses in Poland, this is his mother's new build....
it has, along with every house built there get's100mm external insulation...this is the exact house but with an A.I. garden...
I'm sure this is the min legal requirement there....the house is built with cement blocks, virtually solid and a single skin....

 

[dextadriver]

It will be external cladding
As can be seen there is subsidence at end of bungalow

 

[JOEPRO]

It will be external cladding
As can be seen there is subsidence at end of bungalow

What is the existing wall construction / makeup?

 

[dextadriver]

What is the existing wall construction / makeup?

??? I know nothing about wall construction
Can you explain please
Thanks

 

[Pond frog]

There have been a lot of reports recently about external insulation causing a lot of problems, it mostly seems to be down to poor quality instillation. There seems to be a lot of set up to make money from government grant schemes with little or no quality control.
Like many things if done right by experienced contractors I’m sure it’s excellent but if done badly there’s huge potential for problems.

 

[Mark 5]

It will be external cladding
As can be seen there is subsidence at end of bungalow

Ok, to answer your first post directly and off the back off @Pond frog post.

First your property is council owned and while council work, regardless of types of works undertaken, can be shoddy, I think you should be rest assured that the works proposed, your council and their contractors, should be ok, your council will be aware of bad installation stories and avoid them.

Bear in mind, they are most likely not council but third party contractors, that's the weak link but if your council has used them before, don't worry to much.

If undertaken and installed properly, exterior wall insulation can be very effective, apart from heat retention internally it will also prevent all external walls getting weathered further.

What it won't do is prevent further subsidence if unstable and you should seek further assurance, in writing, from your Council on this before works go ahead, not the contractors and ask if the poor pointing should be dealt with.

Depending on how good/bad your council are, if bad they will fob you off with something like, " the contractors have assured us ", that isn't good enough, the contractors are more than likely not structural surveyors.

Judging from your photos the cracking looks like movement not subsidence and doesn't look to bad.

However the council can have who they want and the type of work undertaken, deal with or choose to ignore issues including spouting fob offs from 3rd parties.

You should expect building work noise but as little inconvenience to you as possible, to tidy up after themselves each day but you will need to be patient and flexible, the lads need to get on with their works.

You should ask the surveyor/contractor what the finnish work will look like, the council should inform you of this before works start but you might not have much choice in the end finnish or get look/finish stated,--it happens.

Hopefully, done correctly and you get to enjoy a warmer home.

 

[minimutly]

If you were asking about cavity wall insulation I would say DON'T!
But external insulation is just that - a cladding that goes on the outside of the outer wall. It can be ok, but sometimes the extent, or the edging to be precise, where it stops (it doesn't go to ground level) can be messy unless done properly. Also, things like the handlebars on kids bikes can pierce it, leaving a depression.
In theory, a good thing, and especially if done well. I would be looking at other jobs before deciding - oh, and it will need painting, and periodically after that.

 

[gaz1]

im a builder by trade

cavity insulation causes damp issues as theres no cavity to get rid of any drips or leaks it also has issues with pointing so any cracks will cause issues in the end

external insulation well is more of a con to a degree whilst it does show the house is well insulated the cavity draft (air bricks ) is well below the threshold heat will still blead out through that point the cavity area is also cold

internal insulation pick wisely first off im not a lover of composite insulation its a fire hazard and if it gets a light its black its also 1/2hr fire boarded

does it insulate well yes it does even with a small wood fire it can hold the heat well via flash heat (flash heat is where you are only heating the air not like storing the heat with walls )

other issues you can cook in a very warm summer as it stores heat within the insulation unless you keep the heat out of the rooms which means curtains closed and keep windows and doors shut
if we get a compound heat summer when its heated up over months in summer you wont get rid of the heat and you will need to find alternatives to cool the area

 

[Gareth J]

Ewi is a bit pointless if you keep the cavity. A well vented cavity will allow cold air to bypass the insulation layer.

With new ewi, you should be at much less risk if you fill the cavity with insulation too though.

 

[knighty]

we're thinking about external insulation, internal won't really suit the house, and we'd lose features we like

already have insulated cavity (done before we moved in, those little beads blown in)

we've been undecided about it... but it looks like we need a new roof, so if we're getting scaffolding anyway we could use that and fit it ourselves, it'll be a long slow job but it is what it is

just typing this I realised we could have the new roof stick out to cover the top of the insulation better, which would be quite nice (we're thinking if fully taking roof off, all new trusses etc. to change the design of it)

 

[gaz1]

as ive already explained if you have a cavity it defeats any external insulation put on the outside of the property

but understand what that cavity does when sunlight is on it in summer it does become heated rather well and can dry out most water issues that get through that cavity its only small but pointing does break down and no one renews there pointing every 5-10 years

external insulation is a con to get the highest looking insulation when in fact its doing nothing on a cavity wall yet on a stupid thermal camera it says it stops heat bleading from the property ( dream on heat is bleading into the cavity area going up into the cold roof down the otherside and out via the air brick or straight out the roof breather )

@ knighty

if you extend outwards on your roof you will have extras and also other issues to deal with

you will need soffits added to your price and in years to come that roof bits will need replacing anyway in less time that what a normal roof would be

plastic soffits do get affected by the heat on the stone or bricks as heat rises off them in direct sunlight

it isnt worth the extra cost on your roof to change to a different type of roof

 

[knighty]

@ knighty

if you extend outwards on your roof you will have extras and also other issues to deal with

you will need soffits added to your price and in years to come that roof bits will need replacing anyway in less time that what a normal roof would be

plastic soffits do get affected by the heat on the stone or bricks as heat rises off them in direct sunlight

it isnt worth the extra cost on your roof to change to a different type of roof

roof already overhangs the walls about about a foot in most places... we were going to get rid of that when we re-roof

right now we have essentially 4 rooves

imagine 2 rooves next to each other with a valley between... then another 2 the same at 90' to those

our thinking is if we need to re-roof anyway might as well swap to 2 rooves and get rid of the valleys

would mean we could open up the loft too.. we don;t need to open it up... but might as well

still waiting on the price tho... it could be crazy

(we're getting rid of most of the chimneys too)

EDIT: google earth roof photo

 

[Dragnet]

Breathability (more correctly vapour-permeability) is fundamental. 'Damp' is almost always condensation caused by a poor understanding of building physics. There is no hard-and-fast rule as individual circumstances have to be taken into account (location, building type, occupants' lifestyle...). Nothing can be applied and expected to work the same way every time. An individual approach is required if you want to be confident of avoiding expensive problems in later years. I'm an architect and, for example, I would never advise cavity wall insulation if a building has not been designed for it. The recent grant systems have caused an awful lot of problems because of the simplistic application of the idea 'insulation = good', when in many cases it can cause condensation, mould or even structural failure.

External insulation in my opinion is often a better general idea as it retains thermal mass, assuming internal radiant heat sources and adequate ventilation. A vapour permeable option such as a lime/cork based render, cork panels, wood-fibre etc. are preferable in my experience to any of the petrochemical foams on the market, quite apart from their parent companies' corrupt records. Don't forget Grenfell.

I can't really say any more than to get a local architect to look at it for you and give you some advice that takes into account your specific construction and local conditions. There are calculations that can be done for worst-case scenarios to ensure condensation does not occur within the wall.

 

[Migmac]

A lot of houses round here were externally insulated. Friends house was one of them, he enquired about getting it done at the same time as the council houses had theres done. He wouldn’t have had it done without fully looking into it. If there were any issues after having it done, he would have mentioned it. His house is a stone built bungalow

 

[knighty]

if we fitted ewi we'd fit one of those whole house heat recovery ventilation thingies.... we're tempted anyway but there's a lot of things going on all at once we'd like to get out of the way first

I think we’d just use standard extractor fans in the bathrooms, don't like the idea of trying to push all that steam/moisture through vents/ducting etc.

 

[Mark 5]

external insulation well is more of a con to a degree whilst it does show the house is well insulated the cavity draft (air bricks ) is well below the threshold heat will still blead out through that point the cavity area is also cold

external insulation is a con to get the highest looking insulation when in fact its doing nothing on a cavity wall yet on a stupid thermal camera it says it stops heat bleading from the property ( dream on heat is bleading into the cavity area going up into the cold roof down the otherside and out via the air brick or straight out the roof breather )

You are mis-understanding the purpose of exterior wall insulation.

No matter how good insulation is, no property, modern or old is heat leak proof.

Exterior wall insulation does help retain heat in the property but it has other benefits to as I explained in reply to @dextadriver.

Poorly installed insulation causes nightmares.

A point being made was as it was a council owned property, I think it highly unlikely the council would jeopardise their own property by employing slap shod methods when it comes to exterior wall insulation.

As it is not their property @dextadriver may have little choice but accept the installation.

Ignoring many exaggerated claims as to benefits, poor design/execution regarding the property to be insulated and final installation, ( not the materials fault ), exterior wall insulation is effective for some properties.

 

[minimutly]

"A point being made was as it was a council owned property, I think it highly unlikely the council would jeopardise their own property by employing slap shod methods when it comes to exterior wall insulation"

Really? It depends if the pen pusher has friends in the right places, the list of failed council "upgrades" is endless. You can lump housing associations in with this lot too.