Cavity wall

fealeranger

Hi all. I am looking into building a house with a perimeter cavity wall with 300mm of pumped insulation as one idea or 100mm pumped cavity and 63mm dryline kingspan inner insulated slab. I spoke to a BER consultant and he put these idea to me. I'm very intrested in th 300mm pumped cavity. Has anybody done this and if yes was it successful. I'm open to different ideas for insulating the perimeter wall so any suggestions would be welcome as I am not up to speed with modern methods and technology. The ground floor area is about 190M sq.

beyondpassive

PM sent with wide cavity photos and details.

fealeranger

I didn't get any pm beyondpassive.

beyondpassive

sorry it was an email

beyondpassive

beyondpassive wrote: »

sorry it was an email

WHat do you think of putting drylining on the internal walls ? many here seem against it.
Or do you prefer more cavity and no drylin, using the internal walls for thermal mass ?

Thanks

BarneyMc

beyondpassive wrote: »

PM sent with wide cavity photos and details.

Could you PM me these also please beyondpassive? Thanks.

Choolips

Hi Beyond Passive, Can you pm me with those details? Sorry for hopping on the bandwagon! Thanks

fealeranger

Deleted User wrote: »

WHat do you think of putting drylining on the internal walls ? many here seem against it.
Or do you prefer more cavity and no drylin, using the internal walls for thermal mass ?

Thanks

Not 100% sure. I'm still looking for a good reason not to put a big cavity and pump it but nobody can give me one. On the Insulated slabs I'm not really sure. They have good and bad points. I have spoke to 2 different BER assors and one is for Drilining and the other is for the 300mm cavity. I'm not a buider or a BER expert so that is why I'm asking about it on here. If I a find any good reason to pick one over the other I will let you know.:)

beyondpassive

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=FoundationDetailsforTender.jpg#!oZZ2QQcurrentZZhttp%3A%2F%2Fs1241.photobucket.com%2Falbums%2Fgg516%2FBeyondpassive%2F%3Faction%3Dview%26current%3Dwindowcloser.jpg

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=FoundationDetailsforTender.jpg

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=EavesDetails.jpg

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=thermals.jpg

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=Roundwoodwidecavity.jpg

http://s1241.photobucket.com/albums/gg516/Beyondpassive/?action=view&current=Roundwoodwidecavity.jpg#!oZZ2QQcurrentZZhttp%3A%2F%2Fs1241.photobucket.com%2Falbums%2Fgg516%2FBeyondpassive%2F%3Faction%3Dview%26current%3Dthermalsfooting.jpg

beyondpassive

Deleted User wrote: »

WHat do you think of putting drylining on the internal walls ? many here seem against it.
Or do you prefer more cavity and no drylin, using the internal walls for thermal mass ?

Why have 2 seperate lines of insulation when you can have 1. I prefer keeping all the insulation in the cavity because.

Robust internal finish good for fixing.
You can use the internal wall to store warmth/coolth and keep internal temps stable.

Dryling is interupted at board joints, floors, partitions, sockets window reveals etc particularly with composite boards. Behind the board the block could be below dew point, this could be a health hazard.

Internal linings messes up on site scheduling particularly for plasterers and electricians.

Insulation can be done after the roof is on and windows in, by insulation installers not blocklayers and can be checked with thermal imaging.

That said there are situations where drylining is appropriate, but it has to be detailed right.

a 300 Cavity presents a big challenge also. But if well thought out by Architect or Technologist, structural eng and energy consultant and you've a good foreman, then its a great choice of build method.

nager

I would agree with beyondpassive above.

That said - also a consideration in how you insulate the house depends on how the house will be used.
If the house will be used throughtout the day - then insulation is best placed on the outter side of the inner leaf. If the house will be occupupied in mornings and evenings only then perhaps insulate internally - as the response time for heating the house is quicker (and consequently loosing the heat), this will depend on how you see the longterm use of the house.

beyondpassive

Cheers Nager, but I think that the responsive building argument is becoming redundant. Consider the situation where you have say a B2 house or a passivhaus space heat demand of 20kWh/m2, with MHRV good airtightness under 2 airchanges and treble glazing,

You would use as much heat ramping up the heat from 15 to 21 degrees as you would maintaining 19-20 degrees constant temperature in the 4 winter months. I'm trying to make the case for a holiday home to use stable temp of 19 all week rather than let the temps fluctuate, I cant see any cost difference in the two utilisation patterns once you are in low energy house territory.

After all if we have a lot of mass and our solar (to meet part L ) is contributing about 800-1000kWh's to the space heating alone , we might as well use that heat and let the thermostats and weather comp just tell the boiler to keep the temp fairly stable. After all the structure takes 7 times more energy than air, so to ramp up from 18 degrees to 20 with the structure at 17 degrees will take a small amount of energy to heat the air because the structure is up at thermal comfort levels anyway.

kboc

Beyond Passive,

I hope you don't mind, I had a quick look through that library of photos and it is quite an impressive collection. From browsing these photos I have a few questions.

In your opinion;

1. Is the insulated slab foundation worth the money

2. (a) What is the best make of wall structure
2. (b) What is the most cost effective wall make to obtain a passive standard

3. If it was your house what would your wall make-up be?

Kind regards,
K

PS i love the style and design of the house in photo #7

beyondpassive

kboc wrote: »

PS i love the style and design of the house in photo #7

ya its a great design by Dermot Bannon, scimpt on interior finishes but its a very high performance of energy efficiency. Builder, American Timber Frame went out of business. We didi the Air tighness testing. See http://www.rte.ie/tv/roomtoimprove/s5p3.html

kboc wrote: »

1. Is the insulated slab foundation worth the money

It really depends on what running costs for heating you are projecting and the shape of the building. For Passivhaus it can be very useful to have a negative cold bridge at the floor/wall junction. Ground condition and point loads are also a factor, Structural engineer input here is critical.

kboc wrote: »

2. (a) What is the best make of wall structure
2. (b) What is the most cost effective wall make to obtain a passive standard

No one size fits all solution. It really depends on what the client preferrence and in Ireland they like the robustness of Masonery in and out. The wall build up isn't a huge cost issue for passivhaus as there is little between the various options. Windows is the big item, we have got quotes ranging from €36k-€80 for certified passivhaus windows alone. I see a distinction between the term Passive and Passivhaus, with Passive we just use the passive approach to find the most appropriate build spec, we're not too precious about the 15kWh/m2.a space heat demand, we're happy enough to get under 20 for most builds. This is because low energy is almost an afterthought, as priorities such as a conservative building form to appease the planners and maxin up the floor space to keep the family on side can take precedent.

But where you have a room in the roof or dormer arangement, then it really matters what you put over, under and between the rafters.

kboc wrote: »

3. If it was your house what would your wall make-up be?

(I wish :-) ) You could make the wall out of wheetabix and cling film far as I'm concerned, its the attention to detail and workmanship that is the critical factor.

beyondpassive

beyondpassive wrote: »

Why have 2 seperate lines of insulation when you can have 1. I prefer keeping all the insulation in the cavity because.

Robust internal finish good for fixing.
You can use the internal wall to store warmth/coolth and keep internal temps stable.

Dryling is interupted at board joints, floors, partitions, sockets window reveals etc particularly with composite boards. Behind the board the block could be below dew point, this could be a health hazard.

Internal linings messes up on site scheduling particularly for plasterers and electricians.

Insulation can be done after the roof is on and windows in, by insulation installers not blocklayers and can be checked with thermal imaging.

That said there are situations where drylining is appropriate, but it has to be detailed right.

a 300 Cavity presents a big challenge also. But if well thought out by Architect or Technologist, structural eng and energy consultant and you've a good foreman, then its a great choice of build method.

Following that, I assume you recommend full cavity fill pumped insulation ? What of concerns i have seen posted here about leakage of water across cavity insulation to the internal leaf ?

I just looked at your posted pics. Are the roof profiles for warm or cold roofs ? Thanks

beyondpassive

Deleted User wrote: »

Following that, I assume you recommend full cavity fill pumped insulation ? What of concerns i have seen posted here about leakage of water across cavity insulation to the internal leaf ?

The bead isn't fully bonded and lets any moisture drain through. with proper detailing of cavity trays this isnt an issue. Vapour pressure will push any dampness to the outside.

Deleted User wrote: »

I just looked at your posted pics. Are the roof profiles for warm or cold roofs ? Thanks

Both.

BarneyMc

What cavity width did you use BeyondPassive? Here's some examples I have:
Cavity of 200mm with beads = U value of 0.15
Cavity of 250mm with beads = U value of 0.13

Perhaps 300mm is going a bit too far?

beyondpassive

BarneyMc wrote: »

What cavity width did you use BeyondPassive? Here's some examples I have:
Cavity of 200mm with beads = U value of 0.15
Cavity of 250mm with beads = U value of 0.13

Perhaps 300mm is going a bit too far?

I've dome 225, 250 and 275mm, with stainless steel heavy duty wall ties, which reduces the overall U-Value. below those you've calculated.

BarneyMc

beyondpassive wrote: »

I've dome 225, 250 and 275mm, with stainless steel heavy duty wall ties, which reduces the overall U-Value. below those you've calculated.

Yeah I guess so. I got quotes for the basalt wall ties but they were VERY expensive. I didn't do any cost-benefit analysis but I don't think they're worth it.

nailer8

I am in a similar position trying to decide what insulation to use. 250 - 300mm cavity is going to make the foot print of the house a lot bigger (or the inside a lot smaller).

I was looking at this product http://www.cavitytherm.com/ claims to be able to achieve U-values of 0.12 on a 150mm cavity. Assuming it is fitted exactly right!!

Has anyone any experience with this product. Do their claims stack up?

BryanF

nailer8 wrote: »

I am in a similar position trying to decide what insulation to use. 250 - 300mm cavity is going to make the foot print of the house a lot bigger (or the inside a lot smaller).

I was looking at this product http://www.cavitytherm.com/ claims to be able to achieve U-values of 0.12 on a 150mm cavity. Assuming it is fitted exactly right!!

Has anyone any experience with this product. Do their claims stack up?

you've answered your own question. how careful are they fitted..

as regards the claim of 0.021 wmk:

‘typical’ wall constructions indicate U values between 0.12 W·m–2·K–1 and 0.26 W·m–2·K–1

(from their BBA, didnt see IAB?) so are we to understand that this value may be 0.13wm2k overall wall Uv or .16wm2k depending on conditions?....

BryanF

BryanF wrote: »

you've answered your own question. how careful are they fitted..

as regards the claim of 0.021 wmk: (from their BBA, didnt see IAB?) so are we to understand that this value may be 0.13wm2k overall wall Uv or .16wm2k depending on conditions?....

Bryan, could you not build the inner leaf first and attach this insulation by an adhesive or bolted or drilled ??. There should be no problem attaching it in this case. If there was a grout behind the board this would help..

nailer8

nailer8 wrote: »

I am in a similar position trying to decide what insulation to use. 250 - 300mm cavity is going to make the foot print of the house a lot bigger (or the inside a lot smaller).

I was looking at this product http://www.cavitytherm.com/ claims to be able to achieve U-values of 0.12 on a 150mm cavity. Assuming it is fitted exactly right!!

Has anyone any experience with this product. Do their claims stack up?

Have you done a comparison on the cost between pumping the cavity and using this board ??

archtech

nailer8 wrote: »

I am in a similar position trying to decide what insulation to use. 250 - 300mm cavity is going to make the foot print of the house a lot bigger (or the inside a lot smaller).

I was looking at this product http://www.cavitytherm.com/ claims to be able to achieve U-values of 0.12 on a 150mm cavity. Assuming it is fitted exactly right!!

Has anyone any experience with this product. Do their claims stack up?

I know of a house currently under construction using the 100mm version of product with drylining. You'll need a 225 inner leaf, if you want to do the job right, to allow the cut joints be taped and sealed and keep the cavity clear.
http://johncloonan.ie/wp-content/uploads/2011/11/P1060488-1024x768.jpg
The blocklayer made up a template for cutting the insulation square and reckons its 30% slower than the standard cavity insulation.

fealeranger

What are the best material for pumping a 300mm cavity wall?

beyondpassive

fealeranger wrote: »

What are the best materials for pumping a 300mm cavity wall?

Expanded polystyrene bead with Graphite (silver colour) Declared lamda 0.033 @12kg/m3 on the BASF product, there is a 'super silver' which is lower.

fealeranger

What would roughly be the cost of this per sq.m/sq.ft?

crazy_kenny

fealeranger wrote: »

Hi all. I am looking into building a house with a perimeter cavity wall with 300mm of pumped insulation as one idea or 100mm pumped cavity and 63mm dryline kingspan inner insulated slab. I spoke to a BER consultant and he put these idea to me. I'm very intrested in th 300mm pumped cavity. Has anybody done this and if yes was it successful. I'm open to different ideas for insulating the perimeter wall so any suggestions would be welcome as I am not up to speed with modern methods and technology. The ground floor area is about 190M sq.

Hi,

Was just wondering what option you chose for your cavity wall construction and if you are happy with it?

Thanks,
BK.

fealeranger

I went with 300mm full fill cavity. It was a little tricky around the doors and windows but well worth it. I now have a very economical house with fantastic wide window's which are a really nice feature. It didn't put a whole lot of extra cost on the overall build either. A good block layer and roofer will help to keep things in order and make life easier.

crazy_kenny

fealeranger wrote: »

I went with 300mm full fill cavity. It was a little tricky around the doors and windows but well worth it. I now have a very economical house with fantastic wide window's which are a really nice feature. It didn't put a whole lot of extra cost on the overall build either. A good block layer and roofer will help to keep things in order and make life easier.

I'm really interested in the 300mm cavity. However. I'm also a little nervous about how competent block layers, carpenterters, window fitters etc. are with the non standard detail.

What type of foundation did you opt for?

Thanks,
BK.

dfader

fealeranger wrote: »

I went with 300mm full fill cavity. It was a little tricky around the doors and windows but well worth it. I now have a very economical house with fantastic wide window's which are a really nice feature. It didn't put a whole lot of extra cost on the overall build either. A good block layer and roofer will help to keep things in order and make life easier.

Fealeranger.
Good to hear your happy with your wide cavity. Can you share with us how exactly you closed the cavities at the reveals. Did you splay the reveals at an angle. Any pics?

gooner99

fealeranger wrote: »

I went with 300mm full fill cavity. It was a little tricky around the doors and windows but well worth it. I now have a very economical house with fantastic wide window's which are a really nice feature. It didn't put a whole lot of extra cost on the overall build either. A good block layer and roofer will help to keep things in order and make life easier.

Hi Fealeranger. I too would be very interested in your experience with the 300mm full fill cavity. Could you post up your experience, advice, details of how things went on-site and any pitfalls you experienced. Also how easy or hard it was to source materials that were needed as a result of the wide cavity and any workarounds that you needed to devise. I am looking at going 250mm or 300mm, so this would be of great help before I start out seeking out professionals and builders to come on board.

fealeranger

My best advice to both dfader and gooner99 is to get in contact with an engineer and ask him. I am not an building engineer so I a not going to advise anybody on how to build their cavity wall. There are a few guys her who are better suited to these questions. beyondpassive and BryanF are 2 guys who know what they are on about so try PM them and see what comes out of it.
Sourcing material is not a problem, it is still a cavity wall just wider than usual. Wall ties are the only unusual thing to get and they were not even that hard.
Closing the cavity around windows is the same as 100mm cavity, 2-3 inch floor insulation, There is a flange that can be used but the company wanted me to buy the pallet and I only needed 25% of the quantity.
Rally it is no different to a normal cavity.

gooner99

fealeranger wrote: »

My best advice to both dfader and gooner99 is to get in contact with an engineer and ask him. I am not an building engineer so I a not going to advise anybody on how to build their cavity wall. There are a few guys her who are better suited to these questions. beyondpassive and BryanF are 2 guys who know what they are on about so try PM them and see what comes out of it.
Sourcing material is not a problem, it is still a cavity wall just wider than usual. Wall ties are the only unusual thing to get and they were not even that hard.
Closing the cavity around windows is the same as 100mm cavity, 2-3 inch floor insulation, There is a flange that can be used but the company wanted me to buy the pallet and I only needed 25% of the quantity.
Rally it is no different to a normal cavity.

Yes totally understand where your coming from. Will check it our with an engineer anyway. Can I ask you from a client point of view, did you find much difference when pricing the wider cavity costs against the old standard 100mm?

fealeranger

A 100mm cavity standard house is around €1200 to insulate(pump cavity). That is a 4 bedroom detached house. 300mm is 3 times as wide as normal cavity so almost 3 times the price of a 100mm cavity. It is still under €4000 euro for 3400sqft house. External insulation would be closer to €45,000:eek:. The cost here speak for it self. I had the choice as it was a new build but I would not like to be facing buying an existing dwelling and having to insulate the outside.

gooner99

fealeranger wrote: »

A 100mm cavity standard house is around €1200 to insulate(pump cavity). That is a 4 bedroom detached house. 300mm is 3 times as wide as normal cavity so almost 3 times the price of a 100mm cavity. It is still under €4000 euro for 3400sqft house. External insulation would be closer to €45,000:eek:. The cost here speak for it self. I had the choice as it was a new build but I would not like to be facing buying an existing dwelling and having to insulate the outside.

Thanks for that.So I guess over the old 100mm the extra costs are an engineer needs to be employed, more wall ties that are special and more expensive are neeed, 2-3 times the amount of bonded bead, slower/trickier and more detailed construction might also push up labour costs. Don't think there would be much more over and above that.

But even at this your right that it will never come close to the cost of external insulation on a new build.

Roundtd181

fealeranger wrote: »

My best advice to both dfader and gooner99 is to get in contact with an engineer and ask him. I am not an building engineer so I a not going to advise anybody on how to build their cavity wall. There are a few guys her who are better suited to these questions. beyondpassive and BryanF are 2 guys who know what they are on about so try PM them and see what comes out of it.
Sourcing material is not a problem, it is still a cavity wall just wider than usual. Wall ties are the only unusual thing to get and they were not even that hard.
Closing the cavity around windows is the same as 100mm cavity, 2-3 inch floor insulation, There is a flange that can be used but the company wanted me to buy the pallet and I only needed 25% of the quantity.
Rally it is no different to a normal cavity.

Great read and great info. Just a few questions!

1. with the 300 cavity where does the window frame site in relatition to this and how was it closed? ie cavity closer and mineral board

2. are the wall ties from ANCON and were they expensive compared to 100mm wall ties

rockabaloo

fealeranger wrote: »

A 100mm cavity standard house is around €1200 to insulate(pump cavity). That is a 4 bedroom detached house. 300mm is 3 times as wide as normal cavity so almost 3 times the price of a 100mm cavity. It is still under €4000 euro for 3400sqft house. External insulation would be closer to €45,000:eek:. The cost here speak for it self. I had the choice as it was a new build but I would not like to be facing buying an existing dwelling and having to insulate the outside.

Is there really any economical incentive of building a house with a cavity this wide. I know there are definitely environmental incentives but purely from a fiscal point of view?

I did some rough calculations for a house the size you suggest. These figures are based on SAP calculations as used in the North.

The heat demand for a year for the house with a 100mm full filled cavity is roughly 14957 kWh/year. For the house if it were built with a 300mm cavity then the demand would be 12987 kWh/year.

This is a difference of 1970 kWh/year.

If mains gas costs 5 cents per kWh then the house with only 100mm cavity insulation would cost an extra 98.50 euros a year to run. If you take a 25 year span then the difference would be 2462.50 euros.

The difference in cost of insulation between the 100mm build and the 300mm build would be 2400 euros. Then add in the extra foundations, wall ties, workmanship, etc. And on top of that for most people the extra 2400 euros at the start of the build will be mortgage money. So it will cost significantly more than what would be saved in heating bills.

My calculations are based on only an average air tight house. So obviously big savings can be made if this were to be improved.

Does anybody have an opinion on this? Am I wrong completely? Are my calculations way off?

I don't mind being wrong so criticise away. I just wanted to ask the question.

beyondpassive

The wide cavity solution is not solely about the u value of the wall planes,

thermal bridges at rising wall, eaves corners and opes, can lose more heat that the walls themselves. The detailing of the wide cavity at these junctions reduces the heat loss significantly

The ply box closer detail works well and is simple, if fixings and membranes are done carefully.

dfader

beyondpassive wrote: »

The wide cavity solution is not solely about the u value of the wall planes,

thermal bridges at rising wall, eaves corners and opes, can lose more heat that the walls themselves. The detailing of the wide cavity at these junctions reduces the heat loss significantly

The ply box closer detail works well and is simple, if fixings and membranes are done carefully.

BP
looks like in that pic that the airtight menbrane will be taped to the outside of the rendering and then skimmed over as opposed to membrane and tape going onto blocks under render. I presume this is to make sequencing of trades easier - am i right. Also wondering does the plywood touch the inside of the dpc at outer leaf or how much do you keep it back.
thanks.
Dfader

rockabaloo

So would you agree that the wider cavity is pointless unless you combine it with a lot of other improvements as well?

Could it be argued that (again from a financial point of view alone) unless you go the whole hog and improve insulation and air tightness to the point where you spend an extra 20,000 or 30,000 on it INSTEAD of spending the money on a central heating system that you would not be better off?

fealeranger

rockabaloo wrote: »

Is there really any economical incentive of building a house with a cavity this wide. I know there are definitely environmental incentives but purely from a fiscal point of view?

I did some rough calculations for a house the size you suggest. These figures are based on SAP calculations as used in the North.

The heat demand for a year for the house with a 100mm full filled cavity is roughly 14957 kWh/year. For the house if it were built with a 300mm cavity then the demand would be 12987 kWh/year.

This is a difference of 1970 kWh/year.

If mains gas costs 5 cents per kWh then the house with only 100mm cavity insulation would cost an extra 98.50 euros a year to run. If you take a 25 year span then the difference would be 2462.50 euros.

The difference in cost of insulation between the 100mm build and the 300mm build would be 2400 euros. Then add in the extra foundations, wall ties, workmanship, etc. And on top of that for most people the extra 2400 euros at the start of the build will be mortgage money. So it will cost significantly more than what would be saved in heating bills.

My calculations are based on only an average air tight house. So obviously big savings can be made if this were to be improved.

Does anybody have an opinion on this? Am I wrong completely? Are my calculations way off?

I don't mind being wrong so criticise away. I just wanted to ask the question.

They are some pretty impressive calculations you have there:rolleyes:. I couldn't say for sure if it is better. It can't be worse :P:cool:. I will let you know when I'm living in it. The only thing I can say when it comes to insulation is it is better to be looking at it than looking for it. I used airtightness material on the doors,windows and the sun room. I believe a house should be able to breathe and too much airtightness takes this away. I dont know where you get the idea that a 300mm cavity creates a big expense in a build. It is just a wider cavity so it has better insulation properties/lower U value if that sounds better. The extra cost is wall ties and pumped cavity insulation and they were not tnat much extra. The way stadards are going a wide cavity wall will be the way forward in the future of building and maybe a dry. Ask for the engineers fee, it is standard and not extra because the wall is wider or some rubbish like that. My engineer didn't charge extra as he said it is his job to come up with the detail.

john_eire

How wide would u need a cavity to get a u value of 0.12W/m2K ?

dfader

john_eire wrote: »

How wide would u need a cavity to get a u value of 0.12W/m2K ?

Depends on thermal conductivity of insulation used, type of wall ties and if using aac blocks so you will not get an exact answer unless you answer for these. there are options and cost differences relating to these materials. however if using normal steel wall ties it will be over 300 cavity.

rockabaloo

john_eire wrote: »

How wide would u need a cavity to get a u value of 0.12W/m2K ?

Agreed.

For example, an insulation with thermal conductivity of 0.033 W/m2K would need to have a 300mm cavity to achieve a U-value of 0.12.

john_eire

(1) Depends on thermal conductivity of insulation used, = full fill with beads not sure which has best thermal conductivity is the super sliver beads the best?
(2) type of wall ties= from reading on here lots of people are using stainless steel ties.
Just got a provisional ber done and he gave me 3 option, two useing plasterboard and one external, but I would like to keep all the insulation in the cavity so was just wondering how wide it would need to be,
I know it's hard to give a exact answer just look for some ideas

rockabaloo

fealeranger wrote: »

I dont know where you get the idea that a 300mm cavity creates a big expense in a build. It is just a wider cavity so it has better insulation properties/lower U value if that sounds better. The extra cost is wall ties and pumped cavity insulation and they were not tnat much extra.

I'm not suggesting it's a big expense. However, it is undoubtedly an extra expense - extra insulation, longer wall ties, extra foundations, extra work around openings, etc. That may not be loads extra but it may be more than what you could potentially save in fuel bills over your time in the house.

fealeranger

rockabaloo wrote: »

I'm not suggesting it's a big expense. However, it is undoubtedly an extra expense - extra insulation, longer wall ties, extra foundations, extra work around openings, etc. That may not be loads extra but it may be more than what you could potentially save in fuel bills over your time in the house.

The Extra cost all in was €4200, wall ties, extra cavity fill sealing around the windows and doors labour and material. How many tanks of oil would that be 7-10 maybe and most people I know can fill their tank 2-3 times a year:eek:. The price of oil is going up. I think my maths are pretty good on this one;). Take a look at the long term outlook rather than the current outlook. winters are colder. It all adds up and insulation is and always will be the best way to keep warm. look at the old cottages. They had no Engineers or BER certs, planning permission or any of these things but they had wide wallls and small windows. Why we ever moved away from these methods is beyond me. They worked well.

rockabaloo

fealeranger wrote: »

The Extra cost all in was €4200, wall ties, extra cavity fill sealing around the windows and doors labour and material. How many tanks of oil would that be 7-10 maybe and most people I know can fill their tank 2-3 times a year:eek:. The price of oil is going up. I think my maths are pretty good on this one;). Take a look at the long term outlook rather than the current outlook. winters are colder. It all adds up and insulation is and always will be the best way to keep warm. look at the old cottages. They had no Engineers or BER certs, planning permission or any of these things but they had wide wallls and small windows. Why we ever moved away from these methods is beyond me. They worked well.

I'm not suggesting you were wrong to do what you did. Obviously the more insulated the house the better.

All I'm asking (playing Devil's Advocate if you like) is can a household that is on mains gas save on fuel bills what they spend on the extra build costs?

My gas bill for the last 12 months for CH and DHW was £285. That was for a 1000 square foot semi-detached. I used roughly 6500 kWh of energy. Obviously if the house was larger and detached then the demand would be greater. But even if you multiply that number by two and a half you would only get a cost of £712.50 for 16250 kWh of energy. My house has 100mm full filled cavity (but only 3/4 of the walls are outside walls) but even if it had a 300mm insulated cavity the financial savings would not be all that significant.

I'm just asking the question, I'm not saying I'm right. I am going to build shortly myself and just want to make the best financial decision I can cos my budget is very tight.

fealeranger

the way I am going at the moment I am on course to furnish the house and finish at €50 per foot square. I was gifted the site so that saved me €30,000. But to include this woulD still come in at €59 per square foot. This is everything done lawn, drive ,council fees, solicitor fees with a very good finish inside. For a contractor will be looking at €65 per square foot for standard finish. This was what I was priced for 100mm cavity and 62.5mm dry line inside. This was to a builders finish. Your doing the right thing in asking plenty questions. Research it the key and helps point you in the right direction. I googled the living daylights out of my house before I started and it was time well spent.

gooner99

fealeranger wrote: »

the way I am going at the moment I am on course to furnish the house and finish at €50 per foot square. I was gifted the site so that saved me €30,000. But to include this woulD still come in at €59 per square foot. This is everything done lawn, drive ,council fees, solicitor fees with a very good finish inside. For a contractor will be looking at €65 per square foot for standard finish. This was what I was priced for 100mm cavity and 62.5mm dry line inside. This was to a builders finish. Your doing the right thing in asking plenty questions. Research it the key and helps point you in the right direction. I googled the living daylights out of my house before I started and it was time well spent.

That's an impressive sq foot price,very well done. I'm googling then hell out of this before I commit to a build method,although wide cavity is my number one based on what I have read so far.nothing like questioning a build method, but surely if we question the advantage of 300mm full fill cavity over 100mm full fill we should also question why external insulation at 10x the price or second generation timber frame would be better over 100mm full fill cavity in terms of heating our new homes,on the assumtion that all of them would have a similar level of airtightness.anyone!