Polystyrene Home Insulate

Senna

Our house was built in 1999 and today i got too see what insulate was used (we bought secondhand). The cavity insulate is 60mm Polystyrene board (about that anyway), i know this isn't used in building anymore, is that because its a poor insulate?
Would a modern material be a lot better than Polystyrene?

BryanF

not necessarily, yes there are lower Thermal_conductivity materials available (meaning they have higher insulating properties). btw thermal conductivity is often mistakenly called 'u-value'.

Polystyrene (the extruded type) is still considered a great insulator with a thermal conductivity of circa .035w/mk. Here's the thermal conductivity of a few other materials.

there are some materials with a lower thermal conductivity that are more popular now, partially as they provide the equivalent insulation in less thickness (and partially due to the power of advertising and a lazy industry), for example kingspan, xtratherm etc (these are generally referred to as either PIR, PUR or phenolic insulation boards at circa 0.25w/mk).

then there are the 'space age' technologies coming out (the likes of Aerogel ), but their still relatively expensive and generally used sparingly. and of course, not to forget the foil 'insulation' products that have still some way to go to prove there worth as anything other than turkey wrapping..

much of the above insulations are petroleum based or high in embodied energy, so if possible (with the situation suitable and budget allowing) i would recommend natural insulation materials sheeps wool, hemp, cellulose, wood fibre, even mineral wool is a lesser energy intensive material and is for the most part recyclable.

if your are enquiring about filling the rest of the cavity, where your polystyrene board is, I would recommend blown bead insulation. there are several on the market, just check that the installer is repeatable and the product has the correct IAB or BBA certification and is installed correctly

Senna

Thanks for the reply. My initial worry was that i had poor insulation, not because the house is cold, but rather because we realised we have a problem with all our windows, so that got me thinking about what else could the builder have taken a short cut with.
We have to take a window out of the house soon, so i'll get to the exact depth of insulate then, but it looks like 60mm. Not too sure if there will be extra space in the cavity if we wanted to pump more in, but i'm happy enough now to know the current insulate isn't terrible.

BryanF

• your current wall U-value is approx 0.45w/m2k
• the seai grant for wall insulation require that the contractor achieves 0.27 W/m2K or better. (this is for drylining or EWI and not applicable to cavity pumping AFAIK)
• current building regs for retro-fit are not that strict at circa 0.35W/m2K
• but for new build many people are building to circa 0.15 w/m2k or lower depending on whether they are compensating for lower values elsewhere

so when you say 'isn't terrible', many sales people could still spout a 20% heat loss figure at you, especially if you told them your house was cold...

I would guess you will have a 40mm cavity and if filled with bonded bead it would bring your overall wall u-value to circa 0.35w/m2k


pump the cavity and fill your attic with mineral wool to a depth of 400mm to start with. if your changing windows consider more insulation, as imo these elements are best replaced at the same time, so as to achieve a good overlap,air-tightness and fit..

Senna

BryanF wrote: »

I would guess you will have a 40mm cavity and if filled with bonded bead it would bring your overall wall u-value to circa 0.35w/m2k

That's not a massive reduction and I'm guessing the cost would be in the thousands, i'm going to find out more about the seai grant, it says €3600 available to a detached house, would the cost to me be much more? (how longs a piece of string?)
Only one window coming out not all of them. I will look into it further but i'm going to wait and see what its like when they take the window out first.

muffler

Senna wrote: »

That's not a massive reduction and I'm guessing the cost would be in the thousands, i'm going to find out more about the seai grant, it says €3600 available to a detached house, would the cost to me be much more? (how longs a piece of string?)
Only one window coming out not all of them. I will look into it further but i'm going to wait and see what its like when they take the window out first.

60mmm aeroboard would have been widely used in houses around the Dru...n area in the mid 90's right up the around 2005 - seriously though it was widely used throughout the county and country as a whole. The usual set up was a 100mm wide cavity with 60mm insulation (some builders used Quinntherm btw) and a 40mm residual cavity. I would doubt if your house was any different from others built around that time.

To upgrade a little (pumped Ecobead and fibreglass attic insulation) will get you a grant of €500 I think from SEI. Depending on your house size you can expect to pay around €1500 - €1800 approx. The grant is then paid after you have the works done and while its not a huge amount its certainly worth looking about. Insulated "dry lining" will cost a lot more btw.

If you do decide to pump the cavities dont listen to any of the installers when they tell you they can do it a lot cheaper if you are not looking for the grant. Its a bit of a scam and by applying for the grant will ensure that you have the job done properly.

If you want a recommendation for a good local installer let me know by PM.

Senna

muffler wrote: »

60mmm aeroboard would have been widely used in houses around the Dru...n area in the mid 90's right up the around 2005 - seriously though it was widely used throughout the county and country as a whole. The usual set up was a 100mm wide cavity with 60mm insulation (some builders used Quinntherm btw) and a 40mm residual cavity. I would doubt if your house was any different from others built around that time.

To upgrade a little (pumped Ecobead and fibreglass attic insulation) will get you a grant of €500 I think from SEI. Depending on your house size you can expect to pay around €1500 - €1800 approx. The grant is then paid after you have the works done and while its not a huge amount its certainly worth looking about. Insulated "dry lining" will cost a lot more btw.

If you do decide to pump the cavities dont listen to any of the installers when they tell you they can do it a lot cheaper if you are not looking for the grant. Its a bit of a scam and by applying for the grant will ensure that you have the job done properly.

If you want a recommendation for a good local installer let me know by PM.

Cheers Muffler, i was thinking €3600 must mean i have to pay double that, so less than 2k isn't as bad. As i said the house isn't cold, but we're getting a few window & draft jobs done which will make the most difference. I was taking to GG, you probably know who i mean. He offered to come up and have a look, but i would prefer to find out what i have at the moment, then get as much info as i can myself before getting him or another company out to see what benefit pumping would do.
I'd be prepared to spend money if it benefited the house, but i just don't think it will benefit enough.
I think my attic is grand, the fibreglass insulate come up nearly over the joists, it was redone only a couple of years ago.

muffler

Senna wrote: »

Cheers Muffler, i was thinking €3600 must mean i have to pay double that, so less than 2k isn't as bad. As i said the house isn't cold, but we're getting a few window & draft jobs done which will make the most difference. I was taking to GG, you probably know who i mean. He offered to come up and have a look, but i would prefer to find out what i have at the moment, then get as much info as i can myself before getting him or another company out to see what benefit pumping would do.
I'd be prepared to spend money if it benefited the house, but i just don't think it will benefit enough.
I think my attic is grand, the fibreglass insulate come up nearly over the joists, it was redone only a couple of years ago.

It was indeed GG I was alluding to. His company is fairly good and as he's also a BER assessor you can get good advice from him regarding other issues and not just the cavity and attic insulation.

Pumping the cavity will not only provide that wee bit more heat retention but will also help with reducing any drafts associated with the cavity.

The €3600 grant you refer to would be for insulating your cavity walls either externally or internally as opposed to simply pumping insulation into the cavity in the middle of the wall. I wouldnt have a notion as to the cost involved for this but Id imagine you would be looking at anything between €8000 - €12000 or possibly more.

If its any help attics would now have 400mm of insulation as opposed to the 100/150mm which would have been the norm when the house was built.

Senna

Was thinking/hopping it would be himself you would recommend. I'll get him out to see what he recommends, but i have a good base of info to go with for the moment, cheers.