Any Structural Engineers about?

[iiyama]

Need a calc for a UB. Had a trawl around on t'internet but came up with nothing, (although maybe I wasnt looking hard enough!).

Basically could do with a little help!

Ta

Ian

[Desiato]

Let me know what you need and I'll have a look tomorrow morning.

[iiyama]

Got a span of 4.2m which will have to support a gable end of brickwork and block. Block is the old clinker type, not lightwieght concrete. Left hand wall which will bear is smae materials, brick and block with 3" cavity. Right hand wall is perpendicular to span and is block so I guess will need a padstone. All masonry is 4".

Ill take a picture or two later and post up and also get an area measurement of gable end which I guess is going to be neaded?

There are no floors to support.

Thanks for the help, let me know if there are any costs involved.

Ian

[Desiato]

iiyama said:

Got a span of 4.2m which will have to support a gable end of brickwork and block. Block is the old clinker type, not lightwieght concrete. Left hand wall which will bear is smae materials, brick and block with 3" cavity. Right hand wall is perpendicular to span and is block so I guess will need a padstone. All masonry is 4".

Ill take a picture or two later and post up and also get an area measurement of gable end which I guess is going to be neaded?

There are no floors to support.

Thanks for the help, let me know if there are any costs involved.

Ian

Hi Ian,

Yes height of gable will be needed. Any considerations required for depth of the section? Given there are no floors to support I assume you will lose any height by going up from the lowest point?
The other consideration is how are you installing it? Is it to be lifted by crane onto scaffolding or Genie lifts at ground level?
Sometimes it's better to have two lighter sections bolted together than one large very heavy section.

[iiyama]

OK, gable is 2.1m. Was thinking along the lines of 2 Beams, one for external leaf, one for internal but Im open to suggestion.



Basically the white line you see running over the window is a concrete slab that has been used as a lintel. Its broken its back, (unsurprisingly!), and I need to get it out. Im planning on moving the wall forward by around 18", so its still within the footprint of the house and run a small leanto roof back to the gable. Window size will remain the same, as will its position within the wall.

ETA that Im hoping to lift them into position with a few mates. However this really depends on the sizes required so if Ive got to get some plant in then sobeit!

Edited by iiyama on Monday 16th August 19:02

[Busamav]

Desiato will no doubt be back with the correct workings ,

but I suspect, as a guess , you could use a pair of channels bolted back to back with spacers , approx sixe 203 x 133 x 35kg

[eps]

So you want a beam to support the opening above the window? Will it only be the same width as the window or wider?

Have you talked to your local Planning Office about your proposals?

Edited by eps on Monday 16th August 20:39

[Busamav]

eps said:

So you want a beam to support the opening above the window? Will it only be the same width as the window or wider?

iiyama said:

Got a span of 4.2m
Ian

[eps]

Busamav said:

eps said:

So you want a beam to support the opening above the window? Will it only be the same width as the window or wider?

iiyama said:

Got a span of 4.2m
Ian

Ah yes, just noticed that!

OP : Is that a clear span, which is wall to wall? I don't think you'll necessarily achieve that.. but shouldn't fall too short of it, with a couple of nibs.

[Desiato]

Your limiting factor on beam size is the deflection, otherwise the plaster on the interior will be liable to crack.
You can use a pair of 150x90 PFC 24, bolted together at 300 nominal centres using M16 bolts. This will be adequate. To give yourself less deflection you could go up to a pair of 180x90 PFC 26, bolted together as before. This should give you less than 5mm of maximum deflection mid-span. Just in case you are not familar with the terminology, the Parallel Flange Channels are 150mm deep with 90 wide flanges and weigh 24kg/m (about 108kg each so easily manhandleable.... as long as you ignore the current manual handling regs )

From the picture it looks like you will be bearing on the brickwork, which is better than the cinder block. Either way you should use a padstone at each end and have a minimum of 100mm of beam each end bearing on the pads.

Hope this helps.

[eps]

I quite like UKCs for these jobs.. But the parallel flanges seem to have good figures against them, especially the higher rated one you mention. As stated the deflection will be just under 5mm, according to all the figures.

The OP could use steel spreader plates instead of padstones, no?

[Desiato]

eps said:

I quite like UKCs for these jobs.. But the parallel flanges seem to have good figures against them, especially the higher rated one you mention. As stated the deflection will be just under 5mm, according to all the figures.

The OP could use steel spreader plates instead of padstones, no?

He could indeed use steel spreader plates. Often preferred as they are often easier to install than traditional padstones.

[iiyama]

The depth of the beam is of no consequence, they will be above the ceiling line, not boxed in below. No rooms in the loft, therfore no plaster.

Bearing to the left of the window will quite possibly be brickwork, bearing to the right I suspect will be block, although at this stage Im not 100% sure. Figured Padstones would be required, could I use 600mm concrete lintels? If not, what spec. are we talking about? Im unfamiliar with spreader plates.

What type of bolts are we talking? HT or standard?

Edited by iiyama on Tuesday 17th August 07:41

Edited by iiyama on Thursday 19th August 07:33

[Desiato]

iiyama said:

Just to clarify then we're talking U beam's and not I. Something along the lines of :- http://www.buildersbeamsonline.co.uk/ProductSpecif... ?

Exactly, you will also need lengths of steel tube or blocks cut to the same width as the cavity to keep the PFCs apart.

iiyama said:

Figured Padstones would be required, could I use 600mm concrete lintels? If not, what spec. are we talking about? Im unfamiliar with spreader plates.

Yes the concrete lintels should be fine. Spreader plates are just pieces of steel plate, normally 10 to 20mm thick that the beam sits on. If you made the plates 600 long, 100 to 150 wide and 12 thick would be more than adequate for your needs.

iiyama said:

What type of bolts are we talking? HT or standard?

I normally recommend grade 8.8 HT bolts but for your loads standard black (4.8) bolts would be sufficient. Alternatively you could buy lengths of 16mm studding and nuts and washers and just cut to length as you go. Most studding is grade 4.8.

Edited by Desiato on Tuesday 17th August 09:34

[iiyama]

Thanks mate, great help. Like I said in original post, let me know if I owe ya anything. You obvioulsy saw my post before I edited. Realised it was a U channel as I hit send. Doh!

Just got do it now!!

[eps]

20mm thick spreader plate? 12mm should suffice.

[Desiato]

eps said:

20mm thick spreader plate? 12mm should suffice.

Indeed it will be, was doing two things at once and had 20 plate on the brain! For this case 20 is somewhat overkill :-D

[eps]

No probs I know what it's like!!!

[Johnniem]

As mentioned by eps, I wouldn't do anything unless you have both planning and building control approval. Note, these are not connected so if you have planning consent then you still need building control approval. Apologies if you have already dealt with this stuff but if you haven't and you choose not to then life will become very difficult and potentially expensive for you, especially when you want to sell the property. Building control will need design drawings (not the planning elevations) and calculations.

[iiyama]

Sorry peeps, led you a bit of a bum steer!

While sorting out the drawings Ive realised that this is not a clear span of 4.2m, there is of course the partition between the bedroom and hallway which runs to the left of the door in the picture. This wall is 1.2m from the right wall which in turn means the longest span is 3m.

Just to clarify the above, left wall, span over window = 3m to middle wall, then another span of 1.2m. The smaller spec beams will be more then adequate for this purpose Im guessing!