Supporting floor above

[P.J.]

Hello all,

I'm removing a ground floor wall that supports the first floor joists (no wall above). I have regs go ahead, beam size etc is defined via the correct people. It's about a 3m span.

I plan to support the ceiling with 2 acrows per side. What should I use inbetween the acrows to support the rest of the ceiling ? Is one scaffold board on each side of the wall OK ? Or, should I use a wooden beam of particular W x H, cut to the correct length ?

Also, do I just take up the slack with the acrows by feel or is there any science behind how far to wind them up i.e. take up slack + 1 turn ?

I guess the beam should sit fully on, and slightly overhanging each padstone ?

Does the beam sit in contact with the underside of the floor joists or is there any packing required ?

Also, what mix should I use to bed in the pasdstones into the wall at each end ?

What is the correct material to use to box in the beam afterwards ?

Many thanks!!!

P.J.

 

[chappers]

A scaffold board will be plenty and iff there is no wall above then 2 acrows will be fine just keep everyone off the floor above or use 3 acrows per side, wind them up until they are tight against the joists, dont over tighten them or you will bow up the floor.

Make sure your beam is long enough for a full 100mm bearing on each padstone and bed these in with a normal mortar mix get another acrow to level up the beam or lift it if possible and pack between the steel and padstone with slate or stainless shims to get it level and up to the underside of the floor joists, if you are sure your steel is level and it is not touching all the joists then either let the other joists down to rest on the steel or if you are sure the floor above is level then pack under the joists accordingly.
The steel needs to be boxed in with two layers of 12.5mm plasterboard to provide 1hrs fire protection (alternatively 1 layer of fire check plasterboard)wedge battens into the web of the steel so you can screw to them

 

[P.J.]

Thanks very much for the info.

I have just a couple more questions:

Can I get slate/steel shims for packing the beam and joists off the shelf or do I need to use tiles / cut my own steel shims ?

What actual mix ratio and type of sand do I use to bed in the padstones ?

How long do the padstones need to go off before I can fit the beam ?

I can rest the beam a full 100mm on each padstone but I can't sit it centrally at one end. How close to one end of a padstone can the beam safely rest ?

Thanks again for the info - almost ready for the off.

Cheers,

P.J.

 

[masona]

See this I hope it does help you !

 

[chappers]

yes just use roofing slates

use a 5:1 sand to cement mix

you can set the beam pretty much straight away providing you have a long enough padstone and dont mix the mortar too wet just as Legs says no mortar between padstone and steel.If you worried or the padstone appears to be moving then overnight would be fine.
Some people advocate letting your steel down almost straight away some say leave overnight before allowing the full weight of the steel onto the padstone.I personally prefer to leave over night if possible

try to set your steel 100mm from the end of the padstone but its not too crucial

 

[P.J.]

Thanks for the info gents.

Yes I saw that interesting discussion on bedding in beams on mortar or slates.

Just a thought: The wall I'm taking away has an outside wall at one end and a 1m pier at 90 degrees at the other (so the wall I'm taking away and the pier for an 'L' shape in plan view). One end of the beam is going to rest on one side of the top of the pier which sounds a bit unsteady to me. I don't really want to leave some of the old wall there to support the beam because I want a flat wall left at both ends. Does a 1m pier sound wide enough to rest the beam on ?

The structural engineer said it would be OK when he did the beam calcs, but I feel like I need a second opinion.

Thank again for the help/advice.

P.J.

 

[chappers]

sounds ok I would trust your SE