Trying to decide on a spec for insulation.

NerdyNed

Hello all,
I'm a complete building greenhorn. The only time I have ever spent on a building site was as a block layers labourer and general dogs body. So please forgive my ignorance.

I've been looking for a site to build a house up here in the wilds of Donegal for over a year now.

I've finally found one I'm interested in. Its already got planning permission for a 220ish Sqm 1.5 story house, which is pretty close to a plan I had in mind should I have had to apply for permission myself.

Because of my lack of experience in the trade, I intend getting a contractor to do the build rather than go direct labour.

Before I take the plan to any builders for quotes, I want to decide on what specifications I'll be using for insulation. I'll be modifying the plans/spec accordingly (without altering anything that would negate the planning permission).

This is something I really want to do as well as budget will allow.

I plan to build using two leafs of 4 inch block-work.

I've looked at timber frame, ICF and SIPS. While they are all better in terms of insulation properties than block-work, whats putting me off is both the lack of local skills with these materials and the costs.

My intention at the minute is to use dry lining on the outer walls and Kingspan (or similar) in the roof.

Other than that, I'm at a loss as to whether its a good idea to fill the cavity or not, and as to whether there are other things I could do to improve insulation.

I've had a look around here in the forums and learnt a lot, but in most of the other threads, the circumstances are different.

I'd appreciate some input/suggestions from those of you who have experience in the trade.

Regards,
Ned

I've attached a section of the plans: (Yes, I realize that the sunroom is in a position where it wont actually get much in the way of sunshine:rolleyes:)

sinnerboy

Ok

Typical build cost x m2

http://www.scs.ie/2010-SCS-House-Rebuilding-Insurance-Guide.pdfcost

Taking Galway rate €1500- Reduction factor for Donegal , say €300 =€1200/m2 cost including professional fees and VAT equates to a mortgage of

1200 X 220 = €264,000.00

At current % rates this will cost about € 1215.00 per month

Now - suppose you build to current average thermal performance levels - BER B3 rating

Suppose you are borderline B2 i.e. 101 kwhrm2/year . Of this 75 kwhrm2/year will be space heating )

http://www.seai.ie/Your_Building/BER/BER_FAQ/FAQ_BER/Assessors/March_Status_Report1.pdf


Now - compare this to passiv house 15 kwhrm2/year

75 - 15 = 60 kwhrm2/year difference in space heating demand

60 x 220 = 13,200 kwhr/year difference

For oil you will pay 10.5 cents per kwhr = €1386.00 per year or €115.15 per month (averaged out ) . Remember this is difference of cost .

http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/Domestic_Fuel_Cost_Comparison_January_2010.pdf

As a % of your mortgage 115.5 * 100 / 1215 = 9.5 %

Now ....

To build to passiv house standard will cost about 10% more .

Putting to one side what may happen to fuel cost - do you want to face the future spending money on oil - or a more comfortable building?

.

sinnerboy

If you do want PH - look for an uninterrupted thermal bridge free insulation wrap of 200mm . Think either

215 solid block with 200 EPS ext wall insulation or
Timber frame closed panel with min 200 insulation

Minimum

No6

hhmmmm 600 to 800 a msq in Donegal. Galway rates are like Dublins, mad!!!:eek:

sinnerboy

Your closer to that ground then me No 6 so ....

Mortage equates to ( 220 * 800 * 4.66 ) / 1000 = €820 per month

Additional fuel spend 115.5 X 100 / 820 = 14 %

No brainer !

NerdyNed

Thanks for your detailed reply sinnerboy.

If I can avoid using oil I will. Harvesting peat is still an option in this part of the country and I'm not averse to taking that route along with burning wood in one form or another.

Thankfully in this part of the country per sqm prices are nowhere near what they are in Galway or Dublin. I could never afford the mortgage if they were. Especially when the price of a site is another 50-60K.

I'd be hoping to get the build done for 130-140K excluding any additional costs for extra insulation. I've been quoted €550 to €700 per sqm as a guide price.

To be honest, external insulation is completely new to me, so I'll have to read up on it.

I take it you dont think dry lining along with additional measures is up to much?

Any other suggestions from anyone?

Thanks again,
Ned

imitation

sinnerboy wrote: »

Ok

Typical build cost x m2

http://www.scs.ie/2010-SCS-House-Rebuilding-Insurance-Guide.pdfcost

Taking Galway rate €1500- Reduction factor for Donegal , say €300 =€1200/m2 cost including professional fees and VAT equates to a mortgage of

1200 X 220 = €264,000.00

At current % rates this will cost about € 1215.00 per month

Now - suppose you build to current average thermal performance levels - BER B3 rating

To build to passiv house standard will cost about 10% more .


.

Pricewise that figure seems very wide of the mark for a 220 sqm house, provided we are talking about a builders finish and little to none site works. I have seen quotes in a similarly priced area as galway for around 1000 euro a sqm for contracted jobs, and that was for an a3 rated house that wasnt your standard square block shape.

Would you think passive is only 10% more ? I`m by no means an expert but it seemed quite expensive to me.

Dont forget as well it ratings its a case of diminishing returns, there is no question that say going from C3 to B1 is worth it, but from A2 to A1 doesnt seem worth the effort to me.

I`m the same when it comes to blocks, ICF looks interesting, but you dont want to be the guy who was the builders first attempt at it. Timber frame seems to be doing alright, but I find it hard to trust timber in the all year around damp climate we have here. I think its easy to get caught up in the European trends on that note too, but we dont have the same deeply cold winters or warm summers that they get.

sinnerboy

1. the price is turnkey including VAT and professional fees . Please read the SCS link for further detail
2. No 6 and I cleared the m2 rate up a couple of posts back .

The build fabric costs more for passiv but when you subtract the conventional heating system the cost falls back to about +10%

The point is not to chase a rating - it is to reduce your demand for energy .
As I have indicated - you will pay in monthly outgoings for the build cost - your mortgage and your energy costs .

We DO require heating in Ireland you may have noticed .

imitation

sinnerboy wrote: »

1. the price is turnkey including VAT and professional fees . Please read the SCS link for further detail
2. No 6 and I cleared the m2 rate up a couple of posts back .

Only noticed that post after I posted myself.

We DO require heating in Ireland you may have noticed .

I have indeed, last winter was no fun. My point is however that we dont get -20C winters, and therefore the same house in Ireland wouldn't require as much heating fuel, which may make the payback not worth it or impractical in some cases.

MicktheMan

imitation wrote: »

Only noticed that post after I posted myself.



I have indeed, last winter was no fun. My point is however that we dont get -20C winters, and therefore the same house in Ireland wouldn't require as much heating fuel, which may make the payback not worth it or impractical in some cases.

You're right, to a point. While the climate is less extreme in Ireland then it is in central europe, the specification of an Irish passive house is also less onerous than a passive house spec for central europe. This then makes the economics of an Irish ph justifiable assuming that the house was designed to be a ph from the start.

sinnerboy

imitation wrote: »

My point is however that we dont get -20C winters, and therefore the same house in Ireland wouldn't require as much heating fuel, which may make the payback not worth it or impractical in some cases.

The "same house" in Ireland vs. in central Europe will require less insulation = less capital investment.

Over the lifetime of a 25 year mortgage it will be profitable to invest in minimising your future fuel bills rather than meet the ongoing costs of failing to do so .

Ask yourself - over the next 25 years , if you take out a mortgage today

1. do you expect your % income spent on mortgage repayments to - over 25 years rise or fall ?
2. do you expect your % income spent on fuel bills to rise or fall