Mortar bed thickness....

[Capable Noob]

My right hand man came down with the dreaded lurgy the night before I had three full readymix loads delivered for footings!  So I had 36m3 to deal with on my own, which was, er, intense to say the least! 

 

Anyway, the upshot is that over the length of about 59 linear metres of footings there is a bit of a difference in levels at a few points.  With something of a wry smile, the architect said it's not the worst he's seen, so that's encouraging...

 

My question is - what are people's opinions / knowledge on the acceptable maximum thickness of the mortar bed when building from the footings with blocks?  And I guess the same question regarding the mortar thicknesses of the next couple of courses or so.  I think there'll be a little jiggery pokery needed and some coursing blocks and cuts (is it ok to cut blocks to suit height-wise?) to get me up to a nice level dpc.   

 

Any input and guidance is much appreciated! 

[Dave Jones]

seen a couple inches lost below dpc. 

[Russell griffiths]

Just think of it coming out a bit crap, then times that by 100, then you will get it to something that you would see on a new building site. 

No matter how crap it is I bet you will get it 10 times better than a site bricky on price work. 

 

Get a level out, laser or water and find the highest points, make a note of these. 

Plot all points so you have a mental picture

mark on a datum stick your finished floor level, damp proof course level and any other relevant markings. 

Start from the high spot and measure down to the footing, see how it works. 

If you are laying blocks on the flat you can easily stick 50mm between them if you need to. 

If they are upright you will struggle with bigger beds. 

 

[Canski]

1 hour ago, Russell griffiths said:

 

 

 

1 hour ago, Russell griffiths said:

Just think of it coming out a bit crap, then times that by 100, then you will get it to something that you would see on a new building site. 

No matter how crap it is I bet you will get it 10 times better than a site bricky on price work. 

Hmm. This is where us site brickies on a price earn our money by avoiding massive bed joints . There are many ways to get over this depending on the levels. Like Russel said you need to find the high point then decide on tight beds at this place say 220 mm for a course of block and 70 mm for a course of brick. The lower parts can be built up to this depending on the levels. If for example the rest is 20 mm lower you can get it out in 2 courses of whatever if its 50 mm you may go for a course of split block with a joint =110 + 2 courses of brick at 160 mm. This would then come level with your first course of 'tight block' Bricklayers try to avoid too thick a bed in the foundations because it slows them down but there are plenty of ways round it so don't worry too much about it. The brickies will moan but that's nothing new or unusual. 

 

An old client of mine used to back the concrete wagon up and tip it in and fiddle with it for 5 mins before ordering packs of LBC's and heading off to the golf club saying 'you're bricklayers aren't you ? get over it' I think his record was 500 mm out of level.

[Brickie]

I’m working in footings for the last couple of years and I doubt it’s anything we haven’t seen before-you can definitely tell when you jump on a plot that was a ‘Friday Afternoon Pour!’

Personally I would check the corners to each other for level-if they’re within 20mm of each other then I wouldn’t worry (I.e. the highest one no more than 20mm higher than the lowest.) If it’s more,even up to say 50mm,find the median & make that your datum. I’m assuming you have at least 525mm from top of concrete to underside of floor? 
Once the corners are up (or profiles in place if they’re using them) then it’s a case of getting over any high spots or dips by laying two courses flat where necessary (where concretes low) or one flat on a tight bed with a coursing brick on top (where concrete is high.) When laying flat,remember to keep the centre of block to the centre of wall or the subsequent courses will tip    

[Capable Noob]

Thanks for the replies everyone!  

 

I have around 800-900mm from top of concrete to finished floor level.

 

Is it ok to use cut blocks?  So if I trim down some blocks to account for the change in level will it compromise the strength of the block?  

[Mr Punter]

You can always use bricks or slate to make up height.  Probably not worth cutting blocks down unless you have to, although no issue structurally.  This morning I got 30 slates for the bricklayers so they can adjust coursing to some steelwork and joists without stupidly thick mortar beds.  50p a slate cash from the roofing merchants.

[Canski]

6 hours ago, Capable Noob said:

Thanks for the replies everyone!  

 

I have around 800-900mm from top of concrete to finished floor level.

 

Is it ok to use cut blocks?  So if I trim down some blocks to account for the change in level will it compromise the strength of the block?  

Yes its fine. 800 is a block split down the middle and laid flat with 3 courses of block on top. 900 is 4 courses. Don't worry the brickies will get over it. if it gets to 850 then its a block flat with a course of brick on it. So many ways of doing it that your brickies 'should' know. I love getting over things like this. They should teach it in college but won't.