Ask a tradesman

Loft Conversions

Loft conversion!

Hi, I am currently in the process of converting my loft. I have the drawing and today they have been approved by the bc to start the work! However I have been advised by the architect to use 8+8 rsj with either side of the house to hold the new weight. But I am confused to the pad stones he has put on the drawing! He has stated to use 900mm+100+150 pad stones to support the steel however I'm sure that this size don't exist so I'm confused to how this drawing has been approved! Can some 1 give me some advice on what to use to support the 8+8 steel's please

4 Answers from MyBuilder Loft Conversion Specialists

Best Answer

The drawing would of been approved by the planning officer, however it does not mean that the works will be signed off by Building Control when they come to inspect it.
Planning are not usually too involved when it comes to detail and structural specifications. Thats what Building Control check on!
The pad stones required are dependant on the substrate going into, the load bearing of the overlying structure and the size of the steel beams that are going to be sitting on top. A structural engineer usually specifies on this.
They can either be poured concrete that is packed with engineering grout when the steel goes in. Or they can be built up using engineering bricks.
When there is no clear specification (which you clearly have not got) we would always ensure to go overboard.

We would ensure there was 400mm load bearing pad under the steel and it spread at least 200mm either side of the steel.
Therefore for your 205x205mm steels you would cut a hole
250mm deep into the wall (your steel should have 200mm bearing)
630mm in height (top of the steel down)
650mm wide.
The front would then be shuttered using plywood leaving a 230mm gap at the top.
The hole can then be filled with concrete to the level of the ply. Allow to fully set and remove the shuttering.
Insert the steel.
jack the steel up and fill the underlying void between the base of the steel and the pad stone with engineering grout. (you may have to order this in advance from your builders merchants).

I would always advise explaining what you are going to do, with your building inspector first. As all are different in different areas, and he may want to add a little something, that would be hard to do after the event !!

Hope this helps
Donovan Contractors


Answered 24th Jan 2013

if this size does not exist from stock you will either have to make them or have someone else make them, you must stick to the drawings, regards Terry.


Answered 23rd Jan 2013

Hi what your architect is asking for is a 900 mil long 150 mil by 100 mil concrete lintel which is wrong,padstones need to be 225 mil deep 150 mil thick and 500 mil long,either pre cast or cast in situ as described by donovan contractors.Also structural steel is calculated by depth width and weight per metre so your architect just asking for a 200 by 200 steel without the weight per metre is also wrong,so structural engineer is next step but have a word with your building inspector he will advise you best.
good luck john


Answered 24th Jan 2013

Wow Tyrone
No wonder your confused , all these conflicting answers and suggestions.
Not to mention even a little confusion between Building control and planning for one of the answerers (if thats a word )

In truth the definitive answer is this !

Yes your architect has stated the size of the steel and pad stones . John is right you should have a weight Kg per m with the steel size , but i'm sure it's either on and you've not mentioned this , or you do need to talk to the architect.

True you have had your plans checked by building control and yes the listed pad stones would fulfil most construction.

But you have options!
The pad stone is to spread the weight.

For example you don't tell us you home construction , if its very light weight blocks ? Go big , long and strong .

Victorian brick could need very little pad.

But a good architect/engineer could work you out a metal plate pad!
A piece of steel 40 mm thick for example would not bend with the whole weight of your house on it .
But having said that non of us can say what to use at all. Just speak back with the architect get him to give you a different spreader plate option and im sure he'll be very happy to .
woody Apex lofts Barnsley


Answered 31st Jan 2013

Post your job to find high quality tradesmen and get free quotes

Can’t find an answer? Ask a new question

Question Categories