Padstone

[Stuar]

The structural engineer that did my beam calculation has specified 660x100x3 courses
Padstones but I cannot find a builders merchant that sells them in this size any ideas welcome.

 

[Mr diy a lot.]

A padstone is just a larger structurally important block of concrete designed to better distribute the weight of a beam. You don’t need to buy an official size - there is no such thing really. You could shutter out the area you need to meet his specs with some ply and pour in your own concrete mix(4 and 1 prob fine). Alternatively, just buy a 2100mm x 100mm x 65mm prestressed concrete lintel, chop it up with a grinder into three lengths and lay it just like three large bricks on top of each other.

 

[Stuar]

Thanks for the reply, the other issue I have is that the original house is a 73mm brick height so 83 with mortar and the other side will be resting on metric size blocks. I can’t understand why they don’t sell imperial blocks it has caused me so many problems with levels.

 

[Mr diy a lot.]

Yeh don’t worry about all this imperial / metric stuff. Imagine your house was an old house built from stone of all shapes and sizes you would still need to set your pads in amongst the irregular stonework. The core principle is to ensure your pad meets his spec to a minimum. It’s ok to make a pad bigger than engineers specs. Prob best to not go smaller in case engineer or building control are pedants and get a tape out(which they almost certainly won’t btw) He has effectively specked a 300mm x 660mm pad so just make sure you have chipped out enough space in the bricks to accommodate at least this.

 

[^woody^]

You need your engineer to specify alternatives, not get ideas as to what may or may not do as a replacement - AFAIK, building inspectors will not accept printouts of DIYnot webpages.

You are unlikely to be able to make your own and make it dense and strong enough and prove it is equivalent to a properly made one

 

[martygturner]

Cast in situ padstones cannot be made on site.???

You need your engineer to specify alternatives, not get ideas as to what may or may not do as a replacement - AFAIK, building inspectors will not accept printouts of DIYnot webpages.

You are unlikely to be able to make your own and make it dense and strong enough and prove it is equivalent to a properly made one

..err what ? there are every day its only 10nmm2 or st2 mix...see https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-5-steelwork/6-5-5-padstones/

Simple box poor and tap, st2 is 1 bag cement to 6 bags of all in ballast (25kg)

 

[Stuar]

Thanks will speak to my structural engineer tomorrow, I just thought you rocked up to a builders merchant and bought one off the shelf. Will the building inspector want a data sheet for the padstone?

 

[Mr diy a lot.]

I have never heard of an inspector wanting paperwork for a padstone. He’ll give it a tap and feel good vibes from your top notch installation, give you the thumbs up and crack on with his day.

 

[^woody^]

Cast in situ padstones cannot be made on site.???


..err what ? there are every day its only 10nmm2 or st2 mix...see https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-5-steelwork/6-5-5-padstones/

Simple box poor and tap, st2 is 1 bag cement to 6 bags of all in ballast (25kg)

Making a padstone is not like making a cake, where you just add sand and cement give a little stir and voila!

 

[^woody^]

I have never heard of an inspector wanting paperwork for a padstone. He’ll give it a tap and feel good vibes from your top notch installation, give you the thumbs up and crack on with his day.

Calculations for a beam include calculations for the bearing, and sometimes for the wall too.

 

[noseall]

Making a padstone is not like making a cake

Myself and my assistant Fanny would beg to differ. As long as you use the correct mix and endeavour to rid the shutter box of air (hammer drill etc) then a domestic padstone is simple to make. Not so easy to manoeuvre and patience (curing time) is essential.

 

[Dereekoo]

Calculations for a beam include calculations for the bearing, and sometimes for the wall too.

Which determines the size of the padstone required not its strength. As long as the padstone is strong enough to distribute the load, and a 1 to 6 mix will be 20N/mm² +, it will do the job

 

[^woody^]

Myself and my assistant Fanny would beg to differ. As long as you use the correct mix and endeavour to rid the shutter box of air (hammer drill etc) then a domestic padstone is simple to make. Not so easy to manoeuvre and patience (curing time) is essential.

And I'm sure you get nice looking blocks of concrete.

But what you don't get is cube tests, slump tests, controlled and adequate curing and confirmed compressive strength.

 

[^woody^]

Which determines the size of the padstone required not its strength. As long as the padstone is strong enough to distribute the load, and a 1 to 6 mix will be 20N/mm² +, it will do the job

I see, the strength of concrete is based solely on how much sand gravel and cement is randomly mixed together.

And the biggest failure of padstones is bearing shear, which is not really related to the strength of the concrete.

 

[noseall]

But what you don't get is cube tests, slump tests, controlled and adequate curing and confirmed compressive strength.

Lol. I'm sure the builders of the Hoover dam will be grateful for your advice. Meanwhile back in domestic bliss, Fanny and me....