Support Wall Removal Advise

[LinusIT]

Hi

After my previous post regarding the length of the universal beam I require getting sorted (turned out dead simple) I have now ordered them and they are coming within a few days. I want to get everything ready for when they arrive so I can crack on over the weekend, I have a few questions I'm hoping you can help with.

The wall I'm taking out is a cavity wall which is in good condition so will be using this as the support. Here's a few pictures and dimensions to get things moving:

Left wall - 940mm

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• LinusIT
• 2 Mar 2015
• 1

Right wall - 1170mm

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• LinusIT
• 2 Mar 2015
• 1

Sliding Doors - 2400mm

First question is how many steel props will I need internally? And is it acceptable to use two scaffolding boards to spread the load across the props? Similar question, how many strongboy props will I need on the external wall?

The load on each wall (internal block and external brick) is 45.81kN according to the calculations done by the structural engineer.

From my reading some people prefer to put the padstones in first and then UBs in after, some the other way around by supporting the UB and then padstones up against it. If there is such a thing, which is the best way or most recommended way?

Do the UBs simply sit on the padstones or should they be on a bed of mortar?

I think I'm asking the impossible here but may aswell ask. Instead of having the 1st floor joists sitting on top of the internal UB is it possible or allowed to have the joists sit inside the UB so that the ceiling can be one big run instead of split up by a box section.

I'll admit that I have never done this before but am not afraid to do the work. I'd rather ask loads of questions and be perfectly clear.

Many thanks for advice in advance.

 

[Alastairreid]

I would use 3 props on the inside and spread the load on scaffold boards on the ceiling and floor.

2 strong boys on the outside.

Mind lay the beams in place before installing the props.

It's easier to put the beams in before the padstones.

You can bolt timber into the web of the beam and fit joist hangers to carry the floor and line the ceiling through.

 

[tony1851]

Just to add to the above:

You sit the beam directly on the padstone, ie without any mortar bedding;
(make sure the padstone is level when you bed it down).

You can have a flush ceiling, but it's a pain if the floor joists run into the beam. You will have to cut the floor joists a little shorter, and care needed to ensure they are not too short. Also messes up the bedroom as well.

 

[LinusIT]

Thanks for the advice.

So would you bolt a piece of timber inside the web so it's flush with the edge of the steel and then hang the joists from that? Basically filling one web with a piece of timber.

If the above is correct then I guess I would have to put both beams in situe, bolt them together and then place the timber inside the web, then bolt it to the beam.

I realise it's allot more work and certain aspects are a pain in the **** to do but it would make such a nicer job. The bedroom above is finished completely apart from having no carpet. I can take the floorboards up no problem without damaging anything.

** Just noticed my spelling mistake on the title, FAIL

 

[Alastairreid]

//www.diynot.com/forums/building/attaching-timber-into-web-of-steel-i-beam.361613/

http://www.jji-joists.co.uk/images/interface/downloads/hangers/sst-steel.pdf

 

[LinusIT]

I'm trying to source the padstones that I need but am having great difficulty. The size specified by the SE is:

265 x 220 x 215h mm padstone
(Under the bearing end of each steel beam, provide and build in a 220mm long x 265mm thick x 215mm high Grade C30 concrete padstone, built in as part of the reconstructed brickwork pillar under the ends of the steel beams and built in solid brickwork with a crushing strength of not less than 30 n/mm2 at each end. Steel beams shall have a min 150mm seating onto the padstones each side.)

I have rang all the local mainstream builders merchants but they can't supply anything of those dimensions.

Any advice on this would be great please.

 

[tony1851]

(Under the bearing end of each steel beam, provide and build in a 220mm long x 265mm thick x 215mm high Grade C30 concrete padstone, built in as part of the reconstructed brickwork pillar under the ends of the steel beams and built in solid brickwork with a crushing strength of not less than 30 n/mm2 at each end. Steel beams shall have a min 150mm seating onto the padstones each side.)

Almost certainly overkill.

Is the wall a cavity wall, or solid 9" thick wall?

 

[LinusIT]

It's a cavity wall.. I have tried contacting the SE but no joy.

 

[tony1851]

If the total factored load on each beam is 46kN, the reaction at each bearing will be 46/2 = 23kN.

That is not very much. If the wall is ordinary common brick in lime mortar and in reasonable condition (post 1920s house??) then there would be no need to re-build the wall at each end.

A 215 long x 140 high x 100 wide conc pad under each beam-end on the existing brickwork would be more than sufficient. I usually specify them cut from lengths of 140 x 100 concrete lintel - they make good padstones.

(Your SE has probably well over-specced the padstones and detailed new brickwork to save himself the bother of doing the figures to show that the existing brickwork, and smaller pads, will suffice. It's the easy way of doing business and unfortunately the client pays in having to build something at greater expense, when it's not really necessary).

 

[LinusIT]

Am I right in thinking that I need to either speak to my original SE or speak to a different one? Not that I don't trust what tony1851 has said as it makes perfect sense to me, just that I don't want to go ahead and then when I get the BCO round, he/she to say "No No No" because I haven't followed the original calcs.

I am going to do this the hard way by hiding the UBs in the floor space and hang the 1st floor joists from timber inside the beam. The beams have arrived today and WOW aren't they heavy. The suppliers have burnt 12mm holes at 600mm centres down the beam, they need a little bit of tidying up but that's no hardship. As I'll be bolting timber inside the web of the beam, do I need to drill more holes in the web purely for fixing the timber inside it or can I use the existing 12mm holes?

The plans state that the beams need to be painted prior to installation. Do I need any special paint or just anti rust type?

Thank you everyone for your help so far, I'm really looking forward to doing the job now.

 

[tony1851]

If you do something other than the design the SE provided, it is likely your inspector will kick off.
But this doesn't mean that what you have done is necessarily non-compliant.

Your options would be to (a) get a 2nd SE to do more realistic figures or (b) ask the 1st SE to re-do his figures. He probably won't do this because he would be making himself look a nit (which he probably is, anyway).

Perhaps just struggle along as best you can with the original scheme, and hope the inspector is realistic.

12mm holes at 600 centres is fine for bolting the timber into the web - the bottom flange will be taking most of the weight, while the bolts just hold it in position.

Strictly no need to paint, unless you're worried about what state the beam will be in 2300, but a couple of coats of hammerite would look nice.

 

[RonnyRaygun]

Out of interest I just ran through some quick calcs for the wall in question, and I agree with Tony.

Obviously I've had to make a few assumptions, but it seems that if 10N bricks are assumed in M4 mortar then the 940mm wall is OK. This allows for the existing loads on the wall, as well as the additional from the beam.

The SE has probably been over conservative and assumed 5N brick in M2 mortar, in which case the pier would need to be rebuilt.

However, I don't think 10N brick in M4 mortar is unreasonable in a 1920s property.

 

[LinusIT]

Just seen the latest replies, no emails came through

I managed to speak to the original SE and he was less than usefull so I have seeked the advice of a different SE. He has re done the calcs and told me the UB I've got it massively over size for the job but as I've got them, I'm stuck with them. He has specified 295 x 215 x 140 padstones which are not impossible to source. The original padstones wouldn't have spanned the width of the cavity wall, it was 30mm too short.

It says somewhere in the plans that the beams must be painted. I bought some anti rust paint and have painted both of them, didn't take too long either.

I'm going to hire a genie lift today and the necessary Acro props and Strong Boy Props. Is 3 props internally and 2 strong boys on the outside sufficient? The total length I'm support is about 4.5m. One thing I can't envisage is where the genie lift goes once the house is support considering the props will be spread equally, not leaving enough gap for the lift.

The existing 12mm holes at 600mm centres are for bolting the two beams together. Can I do as per below?

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• LinusIT
• 13 Mar 2015
• 1

 

[RonnyRaygun]

With regard to bolting the beams together, you need spacer tubes in between them. Something like 50x50 SHS which will stop the flanges of the beams wanting to slide over one another as the bolts are tightened. Or if the beams are not tight to each other it will keep them the correct distance apart.

Not sure if anyone answered previously but yes, bolt the timbers to the webs as shown on the pic.

 

[LinusIT]

I did try and illustrate the spacer tube when making that image, should have noted it up too

Things are getting sorted bit by bit, just need to sort the number of props then it's time to rock n roll.