What weight can breeze blocks support?

Mark M · 5 Feb 2021 at 15:10

I probably shouldn't worry about this but being a bit of a control freak I was wondering what weight breeze blocks can support? At the initial stages of a conversion and the builder has said the steel beams are over 1 tonne in weight which seems a huge amount of weight to me?! There are 3 beams in total and they'll be connected in an I shape with the ends of the "I" being supported at each end (if that makes sense). The house is 20 year old with block and brick construction but will the block work support 1+ tonne?! The calcs have been done by a qualified surveyor so I assume he is aware of the load etc but it just seems a staggering amount of weight to add on but could well be the norm?

Mark M · 5 Feb 2021 at 15:45

Well I’m worried that my house will collapse or the beams will fall and crush my children! Being serious and slightly less dramatic though I’m more interested in if that weight is typical for an extension/conversion? As I said in the OP it seems a staggering amount of weight but I guess it is holding up the house!

Mark M · 9 Feb 2021 at 12:01

Thanks all for the advice and reassurance, guess I just heard the weight and thought it was a massive amount that was being added! Having thought about it further I also have the reassurance of the building inspector who seems very proactive (having been out 3 times already to see when the work is starting) who I assume will check the padstones etc have been correctly spec'd and installed.

Mark M · 10 Feb 2021 at 10:04

DB_SamX said:
Structural engineer here. How long is the beam? Frankly a domestic steel beam being 1T sounds ridiculous. Even at 10m long, which in itself is quite a lengthbof opening to span, its 100kg/m and that size beam must be holding up a storey or two of masonry and floor! I doubt I've specified beams heavier than 50-60 kg/m,mainly on a h&s/practicality of lifting viewpoint.

To your specific question, it depends, maomsry blocks come in 3.6,7,10,20 N/mm2 strength. Padstones are as strong as concrete.

At the end of the day, as long as a professionally qualified structural engineer has been employed to do the maths, you can sleep easy. If your "surveyor" has just gone a selected a beam, then I would worry. Have you had Building Control approve the drawings/calculations or inspected the works? Again that size beam suggests to me it's a substantial bitnof work being undertaken.

Thanks for the reply, the work being carried out isnt that much in my humble opinion (although Im not a builder, clearly!) The kitchen is being extended into the utility room and about 2m's of the garage. Bit of an odd layout currently but I'll end up with a rectangular room 8x4m ish.

The wall is being knocked down between the kitchen and utility room which supports the gable end and 2 x 4.2m beams (bolted together side by side) are being installed. These are relatively light as Ive lifted the ends to make some room in the garage.

The beam which the builder said was a tonne is a 6.3m steel which is being installed from the 2 beams mentioned above which will allow for the wall to be knocked down into the garage. The thing I dont understand is that there is nothing above this part, the utility room is a flat roof and the garage has a pitched roof. Appreciated that pitched roof will have a decent weight to it but its not a 3 story town house thats for sure! Ive not seen this beam yet as was meant to get it on Monday but didnt because of the snow.

There there is a lintel being installed for patio doors at the other end of the long steel. The lintel seems huge too!

Obviously it could be the builder making a meal of it and making the job sound more complex etc but he will have to make 3 trips (already made 2) for the steel because of the weight on his truck (which was a Merc Sprinter drop side by the looks of it). He said the large beam has a 400mm plate on the bottom to support the celling joists which is adding to the weight.

The building inspector has seen the plans I believe, as I emailed the building control a copy when I paid the fee etc. Ive got his mobile so I could always give him a call I guess although just not sure if I am worrying too much and should just let them crack on.

Structural engineer is qualified and insured to the best of my knowledge.

Mark M · 10 Feb 2021 at 13:48

@amigafan2003 those 2 beams that have been installed look to be exactly the same as the 2 in my garage and even look to have the same hole configuration drilled in. My "concern" was with the steel that Ive not seen yet but all seems to be correct and Im worrying about nothing.

I assumed they were "breezeblocks" but Ive probably just got the name mixed up. House has been built about 25 years and the blocks look similar to the ones in your photo.