New Build

Eleni2015

Hi All

My partner and I are just getting our plans drawn up at the minute. We hope to build an airtight home (aiming for 1 or better) with heat recovery and under floor heating. There will be a lot of glass on the south facing side.

As regards to cavity sizes, I'm thinking a 200mm cavity with bonded bead insulation. My architect proposed 150mm cavity with an insulated slab on exterior walls as a cheaper option that gets better u values. What's the downside to this option?

Also with a cavity of 200mm, how many wall ties are needed per square metre?

Thanks in advance for your responses.

Gumbo

Eleni2015 wrote: »

Hi All

My partner and I are just getting our plans drawn up at the minute. We hope to build an airtight home (aiming for 1 or better) with heat recovery and under floor heating. There will be a lot of glass on the south facing side.

As regards to cavity sizes, I'm thinking a 200mm cavity with bonded bead insulation. My architect proposed 150mm cavity with an insulated slab on exterior walls as a cheaper option that gets better u values. What's the downside to this option?

Also with a cavity of 200mm, how many wall ties are needed per square metre?

Thanks in advance for your responses.

1. What does your BER assessment say?
2. What does your engineer say about the wall ties? I'm confused to the randomness of this question tbh. Is there a particular reason why you are worried about the wall ties?

893bet

I don't that insulated slab is cheaper option! Definately more expensive.

BarneyMc

893bet wrote: »

I don't that insulated slab is cheaper option! Definately more expensive.

I would think so also and could give problems with condensation plus greatly reduces thermal mass.

Eleni2015

We havent got a BER assesment done yet. We are only getting the drawings done at the minute. I guess thats the next step before plans go to far.

My question about the wall ties was in relation to the cost of building with a 200mm cavity. The wall ties are around 2euro each and if you needed 10 per square metre (as i was told) it would make it very costly to go this way. I know a structural engineer would tell me exactly but i havent seen one yet.

For an A rated house, is 200mm enough for the cavity? The BER would tell me all this i guess?

JimmyMW

Eleni2015 wrote: »

We havent got a BER assesment done yet. We are only getting the drawings done at the minute. I guess thats the next step before plans go to far.

My question about the wall ties was in relation to the cost of building with a 200mm cavity. The wall ties are around 2euro each and if you needed 10 per square metre (as i was told) it would make it very costly to go this way. I know a structural engineer would tell me exactly but i havent seen one yet.

For an A rated house, is 200mm enough for the cavity? The BER would tell me all this i guess?

See link below for wall ties and spacing recommended by the manufacture, Please note you will need your engineer to sign off on these before use. PS they don't cost even half that inc VAT, depending on quantity. I am doing a 200 cavity at the moment and going to pump it.

I would advise if you architect is suggesting pumping the cavity and insulated slab internally RUN!!!!!!!! as s/he is clueless. This is a complete no no on a new build, several threads here explaining why, look them up.

Cut your losses now and get someone who knows what s/he is at, all of your investment from here on in is going to be based on his/hers knowledge of construction, which seams to be pretty poor by the sounds of it.

http://www.vartryengineering.com/products/extra-long-wall-tie-large-cavities.html

sydthebeat

Eleni2015 wrote: »

We havent got a BER assesment done yet. We are only getting the drawings done at the minute. I guess thats the next step before plans go to far.

1. My question about the wall ties was in relation to the cost of building with a 200mm cavity. The wall ties are around 2euro each and if you needed 10 per square metre (as i was told) it would make it very costly to go this way. I know a structural engineer would tell me exactly but i havent seen one yet.

2. For an A rated house, is 200mm enough for the cavity? The BER would tell me all this i guess?

1. any cavity over 150mm has to be specifically designed by an engineer
so your question is a structural one, which isn't allowed to be answered here

2. you are correct, the only way to know is to have a prelim DEAP assessment done (commonly called a BER)

Eleni2015

Thanks guys.

What are you opinions on basalt ties vs stainless steel ties?

JimmyMW

Eleni2015 wrote: »

Thanks guys.

What are you opinions on basalt ties vs stainless steel ties?

Basalt ties are very expensive (3x) and the thermal bridge is minuscule in the grand scheme of things, for example if you have lest say 700 wall ties in the house thats a thermal bridge of 0.01113m2, having proper detailing with an architect that knows his/hers stuff is much more important, beneath door thresholds etc

Eleni2015

Yeah the basalt ties are expensive. Good to know not to waste money on them! Thanks Jimmy

Can anyone give me a ball park figure for bonded bead insulation per square meter?

JimmyMW

Eleni2015 wrote: »

Yeah the basalt ties are expensive. Good to know not to waste money on them! Thanks Jimmy

Can anyone give me a ball park figure for bonded bead insulation per square meter?

€18-20 + Vat

FiOT

Hi there,

I am just curious as I have gotten a few prices from bonded bead installers in recent days. Also, it might be quite a dim question so apologies in advance.

When you say 18-20e per sqm, how is that measured? Is it per sqm of wall area or floor area?

JimmyMW

FiOT wrote: »

Hi there,

I am just curious as I have gotten a few prices from bonded bead installers in recent days. Also, it might be quite a dim question so apologies in advance.

When you say 18-20e per sqm, how is that measured? Is it per sqm of wall area or floor area?

Per m2 of wall based on the insulation thickness, ie volume. I only have quotes myself and have not yet purchased insulation so ill see how it actually works out.

have2flushtwice

structural advice is not allowed

ht9zni1gs28crp

Ties are usually specified as a number per sq m such as three/four/five per m2 of block

kkelliher

Eleni2015 wrote: »

Hi All

My partner and I are just getting our plans drawn up at the minute. We hope to build an airtight home (aiming for 1 or better) with heat recovery and under floor heating. There will be a lot of glass on the south facing side.

As regards to cavity sizes, I'm thinking a 200mm cavity with bonded bead insulation. My architect proposed 150mm cavity with an insulated slab on exterior walls as a cheaper option that gets better u values. What's the downside to this option?

Also with a cavity of 200mm, how many wall ties are needed per square metre?

Thanks in advance for your responses.

Structural issues are not allowed on Boards, get the advice of your professionals.

THE DON FANUCCI

anybody know what size wall ties are generally used for 150mm cavity?

DOCARCH

THE DON FANUCCI wrote: »

anybody know what size wall ties are generally used for 150mm cavity?

Ask your engineer. Wall ties for wide cavities should be confirmed/specified by an engineer.

893bet

THE DON FANUCCI wrote: »

anybody know what size wall ties are generally used for 150mm cavity?

If you are planning on going it alone for a lot if the build the buy the home bond builders guide.

shugy

JimmyMW wrote: »

€18-20 + Vat

I got quoted 8.50 per sq m in the west. Your price is more than double tgat.

shugy

893bet wrote: »

If you are planning on going it alone for a lot if the build the buy the home bond builders guide.

Is there a new one not due out soon?

893bet

shugy wrote: »

Is there a new one not due out soon?

Think a new one came out 2 years ago. Could be due a reboot again. It is a useful guide for one not connected to any trade.

Gumbo

shugy wrote: »

Is there a new one not due out soon?

893bet wrote: »

Think a new one came out 2 years ago. Could be due a reboot again. It is a useful guide for one not connected to any trade.

Current one is the 7th Edition, issued in 2012.

terrarev

Eleni2015 wrote: »

We havent got a BER assesment done yet. We are only getting the drawings done at the minute. I guess thats the next step before plans go to far.

My question about the wall ties was in relation to the cost of building with a 200mm cavity. The wall ties are around 2euro each and if you needed 10 per square metre (as i was told) it would make it very costly to go this way. I know a structural engineer would tell me exactly but i havent seen one yet.

For an A rated house, is 200mm enough for the cavity? The BER would tell me all this i guess?

If cavity size is a worry would you consider rigid insulation over bead?
Our house has a provisional BER of A2 and has a 150mm cavity with full fill rigid insulation.

JimmyMW

shugy wrote: »

I got quoted 8.50 per sq m in the west. Your price is more than double tgat.

They were ball park figures off the top of my head, however i checked the quotes i hot there now and a 250mm cavity was €16.72/m2 and a 300mm cavity was €18.97/m2 + Vat

What exactly did you get quoted for at €8.50/m2?

stickybookmark

JimmyMW wrote: »

I would advise if you architect is suggesting pumping the cavity and insulated slab internally RUN!!!!!!!! as s/he is clueless. This is a complete no no on a new build, several threads here explaining why, look them up.

Sweeping generalisations!!! There's more than 1 way to skin a cat.

JimmyMW

stickybookmark wrote: »

Sweeping generalisations!!! There's more than 1 way to skin a cat.

I would stand by my "Sweeping generalization" on the above on a new build, a renovation is a different story.

MicktheMan

stickybookmark wrote: »

Sweeping generalisations!!! There's more than 1 way to skin a cat.

So enlighten us. How does your architect propose to achieve 1m3/hr/m2 airtightness or better by using insulated slabs on the internal? Where will the airtightness barrier be in your wall?

madmac187

Lads I'm an engineer and building a house at the minute aswell cavity over 100 is not necessary, just upgrade the insulation quality, use air tightness membrane and ensure your house is airtight. Any cavity over 100 is expensive as everything is geared generally 100 block, 100 between cavity and insulation and 100 block. I would never build a house without cavity. Pumping walls very bad idea. All DPCs in walls and cills can be pushed out by pumping not to mention damp coming through wall as there is no void. So yeah keep it like I suggest it's what I'm doing and getting A2 house. No offence but it's an amateur idea to increase insulation thickness, just spec the product up.

BryanF

madmac187 wrote: »

Lads I'm an engineer and building a house at the minute aswell cavity over 100 is not necessary, just upgrade the insulation quality, use air tightness membrane and ensure your house is airtight. Any cavity over 100 is expensive as everything is geared generally 100 block, 100 between cavity and insulation and 100 block. I would never build a house without cavity. Pumping walls very bad idea. All DPCs in walls and cills can be pushed out by pumping not to mention damp coming through wall as there is no void. So yeah keep it like I suggest it's what I'm doing and getting A2 house. No offence but it's an amateur idea to increase insulation thickness, just spec the product up.

Interested to hear more about your professional approach?

for instance for the duration of construction of junctions at rising walls/floor junction, first floor/walls, wall/roof and pretty much all insulation install In walls are you on site?

Or do you inspect every evening or how are you managing your build?

Very interested to know if you are fortunate enough to be on site constantly and how much for example you think you have saved by going with 100 cavity v wide cavity beads when balanced with a possible loss of earnings due to time taken managing this approach?

IMO most of the wide cavity specification is about eliminating the quality risk and avoiding thermal bridging/looping etc

I'm sure you ticked the Improved thermal bridge factor in deap, and considered the above in your decision making

ht9zni1gs28crp

madmac187 wrote: »

Lads I'm an engineer and building a house at the minute aswell cavity over 100 is not necessary, just upgrade the insulation quality, use air tightness membrane and ensure your house is airtight. Any cavity over 100 is expensive as everything is geared generally 100 block, 100 between cavity and insulation and 100 block. I would never build a house without cavity. Pumping walls very bad idea. All DPCs in walls and cills can be pushed out by pumping not to mention damp coming through wall as there is no void. So yeah keep it like I suggest it's what I'm doing and getting A2 house. No offence but it's an amateur idea to increase insulation thickness, just spec the product up.

OK so...U values, Cold Bridging? Any ideas?. Some block layer you have if his laying of a DPC can be pushed out. Id suggest maybe rethinking your personnel on site.

Also please clarify as to what 'everything' is that is 'geared' towards a 300mm overall buildup?

Not one mention of any U Value in there at all, my money is going where I believe the 'amateur' to be here....

893bet

How can you upgrade the insulation in a 100mm cavity at less than the cost of increasing the cavity size (there is a tiny increase in cost going from 100-150).

sydthebeat

the standard build at the moment is a 150 cavity, there is simply negigble cost difference going from 100 to 150 cavity.

from doing numerous DEAP assessments on new builds, a 100 cavity, even fully filled with PIR insulation, simply does not equate to the most economical compliant methods

Internal insulated plasterboards on the inner face of a new build is a TERRIBLE construction.
a simple search on here will show issue which arise quite quickly with that method.

stickybookmark

MicktheMan wrote: »

So enlighten us. How does your architect propose to achieve 1m3/hr/m2 airtightness or better by using insulated slabs on the internal? Where will the airtightness barrier be in your wall?

I never said I was trying to achieve 1m3/hr/m2?
My target is:
Q50<3m3/m2hr

BarneyMc

madmac187 wrote: »

Lads I'm an engineer and building a house at the minute aswell cavity over 100 is not necessary, just upgrade the insulation quality, use air tightness membrane and ensure your house is airtight. Any cavity over 100 is expensive as everything is geared generally 100 block, 100 between cavity and insulation and 100 block. I would never build a house without cavity. Pumping walls very bad idea. All DPCs in walls and cills can be pushed out by pumping not to mention damp coming through wall as there is no void. So yeah keep it like I suggest it's what I'm doing and getting A2 house. No offence but it's an amateur idea to increase insulation thickness, just spec the product up.

'Spec the product up'?

stickybookmark

BarneyMc wrote: »

'Spec the product up'?

I assume he means pay more for a higher grade of insulation

MicktheMan

stickybookmark wrote: »

I never said I was trying to achieve 1m3/hr/m2?
My target is:
Q50<3m3/m2hr

You're correct. I meant that question for the OP. My bad.

BarneyMc

stickybookmark wrote: »

I assume he means pay more for a higher grade of insulation

OK. From what to what I wonder?

sydthebeat

BarneyMc wrote: »

OK. From what to what I wonder?

seeing as my standard spec at the moment is 150 cavity full fill PIR board, theres not much of an upgrade available

stickybookmark

sydthebeat wrote: »

seeing as my standard spec at the moment is 150 cavity full fill PIR board, theres not much of an upgrade available

Surely these come in different specs with corresponding higher costs?

BarneyMc

stickybookmark wrote: »

Surely these come in different specs with corresponding higher costs?

I think PIR is PIR. There's no 'Super PIR' out there... yet.

sydthebeat

stickybookmark wrote: »

Surely these come in different specs with corresponding higher costs?

not really.. the only 150 full fill PIR board on the market is Xtratherms Cavity Therm (TC = 0.021)

i could spec kingspans phenolic partial fill product (Kooltherm K8) to reach the equivalent u value, but prices are similar and partial fill has more installation issues inherent.

kieran.

BarneyMc wrote: »

I think PIR is PIR. There's no 'Super PIR' out there... yet.

There is ..... well sort of

its call IPN Quadcore it has a lambda value of 0.018w/m²K but is only available in Kingspan Panels division as yet.

sydthebeat

kieran. wrote: »

There is ..... well sort of

its call IPN Quadcore it has a lambda value of 0.018w/m²K but is only available in Kingspan Panels division as yet.

not bba or nsai certed, and we're talking about masonry cavity products

madmac187

miller_63 wrote: »

OK so...U values, Cold Bridging? Any ideas?. Some block layer you have if his laying of a DPC can be pushed out. Id suggest maybe rethinking your personnel on site.

Also please clarify as to what 'everything' is that is 'geared' towards a 300mm overall buildup?

Not one mention of any U Value in there at all, my money is going where I believe the 'amateur' to be here....

I couldn't tell you u value as that depends on products but generally average products such as cavity closer things like that, ties unless specified longer usually more expensive, more ties with less spacing, small on grand scheme of things in costs,bigger window and door reveals, reveals, longer cills, wider dpc strips, all adds up like plastering, more timber around frame. To be honest I won't be there at all, work away just get a guy to inspect it regularly. Don't do direct labour, usually a joke and the cost benefit is not there. People think direct labour is good but I don't think so as I am regularly pulling things down and getting work again in commercial so when it's my house it will have to be right. With regard to thinking I won't pay if it ain't right, if they don't agree it work out well when it leads to an argument. Segregated work packages always look crap if you don't bring in another person to clean up after both something that does not happen in direct labour house builds.

Gumbo

madmac187 wrote: »

I couldn't tell you u value as that depends on products but generally average products such as cavity closer things like that, ties unless specified longer usually more expensive, more ties with less spacing, small on grand scheme of things in costs,bigger window and door reveals, reveals, longer cills, wider dpc strips, all adds up like plastering, more timber around frame. To be honest I won't be there at all, work away just get a guy to inspect it regularly. Don't do direct labour, usually a joke and the cost benefit is not there. People think direct labour is good but I don't think so as I am regularly pulling things down and getting work again in commercial so when it's my house it will have to be right. With regard to thinking I won't pay if it ain't right, if they don't agree it work out well when it leads to an argument. Segregated work packages always look crap if you don't bring in another person to clean up after both something that does not happen in direct labour house builds.

I genuinely believe you are not involved in any form of house construction at all.

ht9zni1gs28crp

kceire wrote: »

I genuinely believe you are not involved in any form of house construction at all.

Your not the only one :eek:

893bet

http://www.boards.ie/vbulletin/showthread.php?p=97660160

He is someway involved.....

Gumbo

893bet wrote: »

http://www.boards.ie/vbulletin/showthread.php?p=97660160

He is someway involved.....

Ohh I don't doubt that. And God knows you shouldn't let an engineer near your cad file without first making a back up

But I think his experience in is the engineering end rather than stating what is and what is not Part L compliant.

I may be wrong and I apologise if I am.

madmac187

kceire wrote: »

I genuinely believe you are not involved in any form of house construction at all.

Yeah whatever.

madmac187

kceire wrote: »

Ohh I don't doubt that. And God knows you shouldn't let an engineer near your car file without first making a back up

But I think his experience in is the engineering end rather than stating what is and what is not Part L compliant.

I may be wrong and I apologise if I am.

I'm looking at it from practicality and ease of build that will mean it's cheaper.

As some don't respect what I have said, I'm not actually bothered in posting anymore. Typical keyboard warriors on boards but anyway.