Window Heights

[PaddyP]

Hi all, 

Possibly a very dim question here but one I can't seem to find the answer to anywhere.

 

When building with ICF blocks are you limited in the heights you can place windows? For example: I want to place a window 900mm from the ground. My ICF blocks are 400mm in height. Does my window have to be placed at 800mm, 1200mm or can the blocks be cut?

 

Maybe this is a system dependant question but interested to hear is this a problem or am I making problems were none exist. 

 

All the best, 

Paddy

[Ferdinand]

Certainly on some systems you can cut blocks, and presumably you can cut the plastic formers too.

 

So I don't see why not.

 

But if it works with whole blocks, why do it?

[Alexphd1]

One of the best things with icf you can cut the blocks while putting them up. We moved a few windows and changed sizes while putting them up but remember new sizes may need steel reinforcements. 

[PaddyP]

1 hour ago, Ferdinand said:

But if it works with whole blocks, why do it?

 

Thank you both very much for the replies. For many of the windows it wouldn't be much of an issue and I wouldn't mind the windows moving slightly to fit the blocks. However for some windows I would like to be more exact. For example we have a large window that is to be flush with the kitchen counter and if it was possible to cut the blocks to achieve this that would be fantastic. 

[Russell griffiths]

You cut the blocks to fit whatever you want. 

A bloke by me designed his house to fit block sizes, all windows exactly block sizes, no cutting and no wastage. 

sounds easy but a bit restrictive.  

[FM2015]

Is your ICF and EPS/XPS variety or a woodcrete?

 

Just remember that if you cut into ANYTHING or remove ANYTHING that is there to keep the block whole, brace it afterwards.

 

Take a Nudura block for example, 457 high.  You can easy reduce that by 100mm from the top and won't have an issue.  Any more, up to 150mm, you might get away with it.  More than 150 and you've effectively got a block that has nothing connecting the two sides together at the top.  Cue the flaring, bursting mess.  If you touch the core structure, the strength must be replaced. Otherwise it's just a former, make it do what you want.

 

Designing houses to the block can be useful, especially if you then get the block by block plan BUT it's very easy to end up a few blocks short.  And in my experience, most architects misunderstand something on course one which makes any kind of planning wasted.  Plus, you take Nudura again as an example, great if the wall is a multiple of 8" but it won't go squarely into a 8' block, ie it won't be a multiple of 96" so there will always be cutting.  It's what experience or diligence does with the off cut that counts.