building block sizes

[sm_jamieson]

I've had delivered some 7N and 3.5N blocks (manufacturer Masterblock), and I've noticed they are all about 5mm smaller than the standard size

440 x 215 (they seem pretty much 100mm wide though). This will not matter for the work I intend to do with these, and its a small difference, and I'm sure they would laugh at the builder's merchant if I complained. But with the accuracy of the bricks you get these days I was surprised. If the thermalite blocks I will use for the main extension walls turn out to be undersize, that will be a pain, since you kind of expect an accurate 10mm joint will get bricks and blocks to line up. I've used bricks before, but not really used blocks for anything. Is this often the case with blocks ? Simon.

[Phil L]

The joints in blockwork can range from 3mm to 50mm(!), both horizontally and diagonally...although it is irrelevant anyway as there isn't anywhere where it will actually matter whether they line up exactly:

1) Brick ties will bend upwards or downwards, and indeed they are made for this, which is why galvanised ones are now banned. 2) At any openings, the blockwork can be easily cut down or packed up.

....on a slightly related note WRT sizes, I recently had the misfortune to lay 225 600mmX600mm flags (paving slabs to southerners) on a patio, drive and front garden - pretty much encapsulating the full house, except none of them were 600 X 600 - the majority were 595 X 597, and some were only 593 X

600....needless to say I was thoroughly pissed off about this as when I lay flags, you cannot get a cigarette paper between the joints, whereas in this case, there were 5mm joints on some of them and even 8mm joints here and there.

The flags were made by RPC {1} and I will never use them again, Marshalls may be slightly more expensive, but at least they are square.

{1} two different batches from different builders merchant's, so they weren't seconds or a 'bad batch'.

[sm_jamieson]

Yes, but this is a pain and would make internal exposed blockwork look ugly (e.g. you can get specially smooth blocks to take paint directly). A block should be the same height as a brick turned on it's end - in fact vertical bricks are often used instead of cutting a block. If not, why bother notionally making bricks and blocks fit with a standard 10mm spacing. I'll obviously not fuss about this since I need to get building, but it's something I will bear in mind in the future !

I'm sure celcon are accurately sized (they are wire-cut), but I will check up on this. I could have been sold rejects - how would I know ?

On an even less slightly related note, wall tiles are the same. You get a neater job if tolerances are good. Anyway this is another thing/snag to add to the memory banks !

Cheers, Simon.

[meow2222]

even slight off-ness sizewise does make a neat job a fair bit harder, but once you've bought them you need to get it done, and the retailer will say the sizs are only nominal... so not much you can do.

NT