correcting unlevel footings

[browfish]

I had my footings poured on saturday and i made a bit of a school boy error. The pegs that i hammered in to guage by levels obviously werent hammered in enought as when the concrete was poured in, they were knocked over resulting in only one level peg left to check against.

After the rains today which have collected in the trench i can see levels easier and along a 14m footing i reckon there is around 3" difference. What is the best way to level this up? Do i start with a full block at he lowest point and simply trim the blocks in height to provide a level first course?

 

[stuart45]

Do i start with a full block at he lowest point and simply trim the blocks in height to provide a level first course?

You can, but it's a lot of work. Or start at the highest with a whole block, and use a brick under a block at the other. Put the line up and run it in.
You can cheat a bit and use a few LBC commons for the cuts. Use some slate as well as the joints first get bigger.

 

[^woody^]

Always gauge down from a level, not up from the concrete

Set up your new pegs for DPC level and then work out what this means in courses down to the concrete.

3" is a course of bricks, so you will just need some extra bricks for part way at the low end

 

[browfish]

I am using thermalite blocks from concrete up. Can i use normal bricks in places too. I thought you werent supposed ot mix materials as the expand/shrink at different rates?

Also, i am a little concerened about the amount of water at the moment. I know we have had a lot of rain recently but the water table seems to have risen by about a metre in the last week. The bottom of the foundations were fine and dry when i dug them, now i have a few inches of water sat on top of my foundations only about 6" below the soil. The thermalite turbos that i am using are fine below ground but will this amount of moister do any damage to them or the mortar?

 

[browfish]

Also, as this is an extension, if the existing DPC/brickwork is not completeley level across the lenght of the house, should i install mine at the same slope or perfectly level? If the later, what would the detail be where the new wall meets the old at differnt levels?

 

[^woody^]

Mixing bricks and blocks relates to thermal material differences in rooms, nothing to do with foundations

There is nothing wrong with water in foundations. Just bail them out when laying the blockwork. Don't forget your blocks are going to be soaking when when built, so water is not a problem for them

Normally things are built level, not on a slant. I can't see how your existing DPC could be much out of level, and in any case it may not be possible to achieve perfection in the new work

 

[browfish]

Thats what i figured. Roll on the dry weather then all set to start then, except the bloody builders merchant delivered 10 pallets of the wrong blocks today

 

[hammerswinger]

Hi,
Sorry to throw this at you but is there any particular reason why you are using Thermalites?

This is just my personal opinion but I would avoid using them if you can especially below ground level, in fact I would advise you not to use them at all if possible and use standard concrete blocks which will produce a much more solid job.


Cheers.

 

[karlosmaximos]

Do you mean 100mm thermalites or 300/275mm trench blocks? Alot easier if your footings are out, but not 3"