inner cavity wall question

jagrace

hi,
I have a question on whats best for the inner cavity wall on my build(dormor 3500sq ft with concrete first floor). I cant decide whether to use the quinn thermal block or use a standard block and dry line the inner leaf. what would give me the best u- value and cost ? also i will be carrying the weight of a concrete floor upstairs will the quinn blocks be as good as normal blocks for this job. they seem a little brittle to me? another question i am putting in UFH and plan to put in a 6 inch soap bar on top of my first row of blocks made up of 100 mm insulation, then UFH and screed(finished floor to the top of this block. Is this a good idea before any blocks are built up in the house or should i wait and try to finish the floor at a later date maybe using battens around the walls to screed off? Thanks in advance got some great advice the last time i posted.

sydthebeat

firstly, a concrete slab first floor would mean that you would have to incorporate 150mm quinnlite blocks as your innerleaf.

Whether dryling with insulation is better than quinnlite inner leaf depends on the thickness of insulation applied. I personally would think a more economical method would be to incorporate thicker insulation in the cavity and then use a quinnlite inner leaf.

the best make up for a floor with UFh is
65 screed (or thin screed such as easi-screed)
UFH system
100mm PU or PIR insulation
150mm concrete slab

ollie30

keep in mind that if you do use quinnlite your plasterer will probably still want to plasterboard the lite blocks due to the way they are very hard to plaster

YourAverageJoe

Hi,

I am trying to make the same decision now myself, quinn-lite or std block for inner leaf. Have searched the forum but not too many comments on this subject.

My question is, has anyone here got actual experience of using these quinn-lite blocks. I understand the thermal advantages but is there any negatives (apart from the plastering), for example structurally sound?, hard to work with?, difficulties incorporating with other building elements for eample doors/floors/windows?

Thanks

RKQ

YourAverageJoe wrote: »

My question is, has anyone here got actual experience of using these quinn-lite blocks. I understand the thermal advantages but is there any negatives (apart from the plastering), for example structurally sound?, hard to work with?, difficulties incorporating with other building elements for eample doors/floors/windows?

They are very popular in the UK and will increase here, especially are Document L improves.

IMO they are easy to cut, which is great for chasing walls for electrics. Some Blocklayers love them because they are so light to carry and easy to cut. While others don't like them because they soak water out of mortar! Different strokes.....

I'd agree with Syd as regards cost. Why not contact Quinns Saleman and go look at afew local houses or talk to their recent Clients?

YourAverageJoe

Thanks for the info, very interesting.

What is the consequences of the blocks drawing the water out of the mortar? Does it mean they dont set right?

Slig

YourAverageJoe wrote: »

Thanks for the info, very interesting.

What is the consequences of the blocks drawing the water out of the mortar? Does it mean they dont set right?

The main problem with lightweight blockwork is that they soak the water out of the plaster causing it to set quickly and fall off the wall. This can be overcome by soaking the blocks before plastering them.

They have the same structural strenght as standard blockwork, more in some cases.

Quinn arent the only manufacturer, Acheson & Glover also do a lightweight block which the say is much easier to plaster than the Quinn but I havent yet seen the proof on-site.

YourAverageJoe

thanks

thunderRoad

Hi guys,
Starting a new build in galway in the coming weeks and was thinking of using QL or similar for the inner leaf of a 150mm cavity, my engineer has never used them and is unsure whether or not they are a good job, he seemed to think there might be an issue with the wall plate straps not holding very well as the house will have a hipped roof, anyone have any experience of this