Natural Stone/Outer Block

soloeffort79

How much cement would i need to put between my outer leaf block and the natural stone on the front of my house. The stone is about 5/6" thick so the problem I have at the moment is that my stone mason wants to have 8" from the outer block to the outside of the stone. This is causing a problem with my window sills as i only have about 3/4" of the sill coming out. Anyone any suggestions on what I can do?

Mellor

Why does he want to leave 8"?

That would mean over 7" between the blockwork and stone. What was his reason for this.

soloeffort79

That's what he tell's me he normally does...I don't see the reason for 8" if the stone is roughly 5 and then adding 2/3" of sand/cement between the stone and outer block...What is the norm?

Slig

Mellor wrote: »

Why does he want to leave 8"?

That would mean over 7" between the blockwork and stone. What was his reason for this.

I think he means outer leaf to outer leaf of 8" which to us non-americans is 200mm, thats pretty standard for natural stone cladding. The trend is then to use the stone as your outer leaf and pull the cill out by 100mm.

There is always a larger cill needed for with stonework, looks better aswell if its abit chunkier.

Mellor

Yeah, I understood that, the 7" is a typo, I meant 3" between the block and stone.
If his measurements are correct thats two much.

To be fair, the OP is a bit all ove the place with number so maybe not what he is saying

soloeffort79

Sorry guys, I'll start again
I have an inner block,cavity 100mm, outer block. On the outer block I'm adding natural cut stone. I have already installed my precast window sills. They are coming out 8" from the outer block.The biggest ones that are available so stone can be added I'm told unless i get sill specially made. The cut stone is roughly 5/6" thick so in theory I should have enough space to add the stone and for the window sills to come out far enough over the stone..Stone mason is adding 3" of sand/cement between stone and outer block which is pushing out too far under the sills..

Slig

Is the window cill in the same location as the other cills (resting on the outer leaf and projecting 50mm into the cavity) or will you be moving the window out so that it will be flush with the outer leaf of blockwork.

It sounds to me that the window will be in the same position as in all the other (non stone clad windows) which will leave you problems when the stone cladding is finished. The most common way around these problems would be to move out the window 100mm. This leaves no untidy reveals to be rendered.

atech

Slig wrote: »

Is the window cill in the same location as the other cills (resting on the outer leaf and projecting 50mm into the cavity) or will you be moving the window out so that it will be flush with the outer leaf of blockwork.

It sounds to me that the window will be in the same position as in all the other (non stone clad windows) which will leave you problems when the stone cladding is finished. The most common way around these problems would be to move out the window 100mm. This leaves no untidy reveals to be rendered.

+1
Although you would still need at least a 11" wide cill though

Be careful when doing this though as the window is no longer in line with the insulation so damp/cold bridging issues may arise unless it had been detailed properly 1st.

See attached detail I did for a previous thread.

Probably not much help to the OP now though.

Mellor

soloeffort79 wrote: »

Sorry guys, I'll start again
I have an inner block,cavity 100mm, outer block. On the outer block I'm adding natural cut stone. I have already installed my precast window sills. They are coming out 8" from the outer block.The biggest ones that are available so stone can be added I'm told unless i get sill specially made. The cut stone is roughly 5/6" thick so in theory I should have enough space to add the stone and for the window sills to come out far enough over the stone..Stone mason is adding 3" of sand/cement between stone and outer block which is pushing out too far under the sills..

You cill sounds big enough, but the 3" is causing problems, if this was 1" you have 2" projection, which is enough imo

Any more and the cill needs to be moved, and re-detailed

pat hughes

how mutch stone work are you building and what type off stone are you using i am a stone mason when i am building stone i alwas use a sill off 300m it sounds to me your mason will have to cut the stone to sute the sills

hbarstone

what stone you using on house, can be built at 5 or 6 inches to give required projection no problem, usually i too build stone 8 inches but when required for reason like yours can narrow stone to overcome problem, if any futher queries can message me, be glad give any advice can