quinn lite blocks inner leaf

johnpawl

OK, this is what I'm thinking... 100mm platered outer leaf, 150mm cavity pumped, 100 mm inner leaf concrete block, scratch coat and skim. Right, I'm thinking of using 2 courses of quinn lites at bottom and top of inner leaf to combat cold bridging. Question is, is it okay to lay concrete blocks on top of quinn lites? Thinkin of a precast concrete first floor, would 100mmm quinn lites be able to support this?
Would I have to use 150 mm blocks?
Also would i have to get special wall ties for wider cavity?
Can I get wall ties that are less susceptible to conducting heat out?
If I wanted to increase cavity to 200 mm am I wasting money?
With a 200 mm cavity, is it possible to use 100mm blocks or do they have to be increased?
Sorry about all the questions but its getting to the stage where I need to make my mind up fairly quickly.. Thanks..

sinnerboy

If you are using a concrete upper floor you must hire a structural engineer to design and oversee this work .

Opinion is divided as to whether a 100mm leaf should take a concrete upper floor load ( I am in the "NO" camp")

So your engineer should make a call on

- the inner leaf thickness
- the suitability of using quinn lites as you describe
- the cavity width
- the wall ties

If you increase the cavity beyond 150mm - you must use a structural engineer

Normally forum rules dictate no product names however as far as I know only this tie is certified for wide cavities and low thermal conductivity .

If as - I assume you will be - appointing an engineer then yes , increasing the cavity to 200mm is a smart move . The extra insulation that can be accommodated is very worthwhile in terms of energy saving . Beyond 200mm imo is a point of diminishing returns . ( I can't proove this point - it is a consensus I have seen build up with others )

ardara1

johnpawl wrote: »

OK, this is what I'm thinking... 100mm platered outer leaf, 150mm cavity pumped, 100 mm inner leaf concrete block, scratch coat and skim. Right, I'm thinking of using 2 courses of quinn lites at bottom and top of inner leaf to combat cold bridging. Question is, is it okay to lay concrete blocks on top of quinn lites? Thinkin of a precast concrete first floor, would 100mmm quinn lites be able to support this?
Would I have to use 150 mm blocks?
Also would i have to get special wall ties for wider cavity?
Can I get wall ties that are less susceptible to conducting heat out?
If I wanted to increase cavity to 200 mm am I wasting money?
With a 200 mm cavity, is it possible to use 100mm blocks or do they have to be increased?
Sorry about all the questions but its getting to the stage where I need to make my mind up fairly quickly.. Thanks..

1. The break between differing block types will effect drying out of plastre and resulting in cracking. If done the junction would need to be hidden - behind skirting at floor junction - or thermal liner below ceiling.

2. the aerated block will assist in improving the thermal bridging PSI value at the floor junction - but it is also there to improve the jambs/heads/cills & gable junctions - no sense in solving just one junction - how do you deal wit the rest?

3. Pushing a cavity to 210mm increases the costs for a semi (UK) up by £2570 or a detached by £4512. Before insulation costs are considered on the semi - the additional costs were £28.25 of insulated wall area - then addt he price of the insulation (Low conductivity ties were used.)

johnpawl

ardara1 wrote: »

1. The break between differing block types will effect drying out of plastre and resulting in cracking. If done the junction would need to be hidden - behind skirting at floor junction - or thermal liner below ceiling.

2. the aerated block will assist in improving the thermal bridging PSI value at the floor junction - but it is also there to improve the jambs/heads/cills & gable junctions - no sense in solving just one junction - how do you deal wit the rest?

3. Pushing a cavity to 210mm increases the costs for a semi (UK) up by £2570 or a detached by £4512. Before insulation costs are considered on the semi - the additional costs were £28.25 of insulated wall area - then addt he price of the insulation (Low conductivity ties were used.)

Hey ardara, thanks for the reply...
I understand your point about keeping the joint between the differing block types out of sight due to cracking, but if i was to use the aerated block to improve jambs/heads/cills & gable junctions, how would I hide the joint??

johnpawl

sinnerboy wrote: »

If you are using a concrete upper floor you must hire a structural engineer to design and oversee this work .

Opinion is divided as to whether a 100mm leaf should take a concrete upper floor load ( I am in the "NO" camp")

So your engineer should make a call on

- the inner leaf thickness
- the suitability of using quinn lites as you describe
- the cavity width
- the wall ties

If you increase the cavity beyond 150mm - you must use a structural engineer

Normally forum rules dictate no product names however as far as I know only this tie is certified for wide cavities and low thermal conductivity .

If as - I assume you will be - appointing an engineer then yes , increasing the cavity to 200mm is a smart move . The extra insulation that can be accommodated is very worthwhile in terms of energy saving . Beyond 200mm imo is a point of diminishing returns . ( I can't proove this point - it is a consensus I have seen build up with others )

Thanks for reply sinnerboy, would you recommend a 150mm inner leaf block so as opposed to 100mm or what'd be your approach..

sinnerboy

I would look for 100 outer - 200 cavity pumped - 150 inner leaf . As I must stress - you must have a structural engineer to verify this is ok for your particular house design .

FesterBeatty

The wall thickness is not solely determined by the vertically imposed load. Naturally your engineer(!) will need to analyse the wall's capacity to cater for wind load...i.e if it's 3m high x 6m long and unrestrained by cross walls then a 150mm solid block wont work - and a quinn lite certainly will not! But, of course, all structures must be analysed individually - so no doubt your engineer will look after that.

ardara1

johnpawl wrote: »

Hey ardara, thanks for the reply...
I understand your point about keeping the joint between the differing block types out of sight due to cracking, but if i was to use the aerated block to improve jambs/heads/cills & gable junctions, how would I hide the joint??

Exactly

johnpawl

ardara1 wrote: »

Exactly

As you advocate the use of the aerated blocks to solve jambs cills etc. I assume you have a solution to address the joint cracking??

ardara1

johnpawl wrote: »

As you advocate the use of the aerated blocks to solve jambs cills etc. I assume you have a solution to address the joint cracking??

Either don't mix the blocks - or cover junctions with liners on ceilings and skirting board on floors - but mixing the blocks only solves the bridging at floor junction - not the jambs, sills, gables, corners, etc, etc, etc. - Dont ignore them.

dfader

I think what Adara is suggesing is that you do the entire inner leaf with 150mm quinnlites. Obviously this is more expensive but the overall U value of your walls will be much improved due to the fact that the thermal conductivity of quinnlites is something like 0.17 as opposed to 1.33 for dense blocks.

FesterBeatty wrote: »

The wall thickness is not solely determined by the vertically imposed load. Naturally your engineer(!) will need to analyse the wall's capacity to cater for wind load...i.e if it's 3m high x 6m long and unrestrained by cross walls then a 150mm solid block wont work - and a quinn lite certainly will not! But, of course, all structures must be analysed individually - so no doubt your engineer will look after that.

festerbeatty, surely the wind loading is not a major concern for a domestic build - its not soley a stand alone 150mm block wall as you seem to be referring to, its a 150mm wall tied into a 100mm block wall filled with bead with lateral support given by internal block walls and first floor if its two story.

FesterBeatty

festerbeatty, surely the wind loading is not a major concern for a domestic build - its not soley a stand alone 150mm block wall as you seem to be referring to, its a 150mm wall tied into a 100mm block wall filled with bead with lateral support given by internal block walls and first floor if its two story.

Might not be the governing factor for the design...but then again it might be. Some domestic wall panels which I've designed have been significantly large and require strengthening in the form of bed joint reinforcement, wind posts, band beams etc etc...But if you dont get an engineer to design/check it for you then you obviously run quite a serious risk. Then again, you might get lucky and it might stand up for ever by pure luck, as opposed to design!

johnpawl

If i did decide to do the entire inner leaf in quinn lites, wouldn't that just be like putting on insulated slabs on the inside??
I've never used those blocks, are they ok for fixing things to, such as kitchen units etc?
Can you use a quinn lite as a cavity closer, can you express nail the wall plate onto one same as a normal block?
Are they ok to plaster??
Any help appreciated...

sinnerboy

All valid issues - no easy answers .

One approach to take - fuzzy logic warning here - is to use conventional blocks above dpc - with wide fill cavity which you detail as far as possible the way you would detail external wall insulation - regarding the outer leaf as simple rain screen , thermally i.e. internal and external leafs never touch .

This is not easy to explain properly without lots of expertly prepared drawings - so I am not going to try here- please don't ask

PS this means 215 inner leaf

johnpawl

sinnerboy wrote: »

All valid issues - no easy answers .

One approach to take - fuzzy logic warning here - is to use conventional blocks above dpc - with wide fill cavity which you detail as far as possible the way you would detail external wall insulation - regarding the outer leaf as simple rain screen , thermally i.e. internal and external leafs never touch .

This is not easy to explain properly without lots of expertly prepared drawings - so I am not going to try here- please don't ask

PS this means 215 inner leaf

haha fair enough I wont try to get you to write a book on it...Just one last question I'll ask if you dont mind...I wont get on your case bout cills, reveals etc and cold bridging I'll try figure that by other means, just this... if I used quinn lites below dpc or an insulated foundation to deal with that junction, used normal blocks on inner leaf, how would i deal with the cavity closer?? Thanks again....

sinnerboy

Sorry - the point at where discussion ends and becomes work that should be paid for has been reached .

I hope you understand this .

johnpawl

sinnerboy wrote: »

Sorry - the point at where discussion ends and becomes work that should be paid for has been reached .

I hope you understand this .

No prob, thanks anyway

James T aka Mr. James T

how did you get on withthe build thinking of doingt the same myself.
did you sort out how you close the cavity