Beefy ridge beam check and plan to reduce size

[NandM]

My SE has spec'd a fairly hefty ridge beam for a 9.6m span @ 254x254x89UC. This will be supporting either 9x2 or 10x2 rafters with clay roof tiles and in-roof solar.

 

A couple of builders I've had over were surprised by the size of the beam and the challenge of getting it up. I could hire a crane, but I'm wondering if it has been over spec'd and/or whether I can build in some additional support to take some load and reduce the beam size.. I've emailed the SE with my query, but it would be great to get your thoughts as well. I proposed a load bearing wall in the bathroom and, if it helps a lot, a column or pier in the bedroom. Both would be on top of existing load bearing walls.

[JohnMo]

7 minutes ago, NandM said:

254x254x89UC

Ask why not a glulam beam (or similar), at least you don't get a massive thermal bridge.

 

This is mine being lifted in with a pretty small tele handler, think that beam is about 11-12m long.

 

[saveasteading]

9 minutes ago, NandM said:

builders I've had over were surprised by the size of the beam 

It's a very long span taking a lot of load. It looks right to me .

The weight would reduce if you used a deeper beam (perhaps about 450 or 500 deep) instead of that chunky section. But deeper will likely interfere with your headroom/ aesthetics.

[NandM]

25 minutes ago, JohnMo said:

Ask why not a glulam beam (or similar), at least you don't get a massive thermal bridge.

 

This is mine being lifted in with a pretty small tele handler, think that beam is about 11-12m long.

 

 

 

 

I assumed thermal bridge would be reduced somewhat with it being under the rafters, but I'll look into glulam and ask the question.

[Buzz]

17 minutes ago, JohnMo said:

Ask why not a glulam beam (or similar), at least you don't get a massive thermal bridge.

 

This is mine being lifted in with a pretty small tele handler, think that beam is about 11-12m long.

 

Another fan of glulam beams here , this one was just over 12m and tele handler friendly , you can leave some of it on show rather than boxing around steels. 

[Moonshine]

5 minutes ago, Buzz said:

Another fan of glulam beams here , this one was just over 12m and tele handler friendly , you can leave some of it on show rather than boxing around steels. 

 

Do you not need to fire protect them?

[JohnMo]

20 minutes ago, Moonshine said:

 

Do you not need to fire protect them?

We didn't 

[joe90]

Another fan of glulams here 👍

[saveasteading]

1 hour ago, Moonshine said:

Do you not need to fire protect them?

Good question. The building regs may imply yes. The reality is it won't burn down until the rest is already gone. 

[Russell griffiths]

1 hour ago, Moonshine said:

 

Do you not need to fire protect them?

Not unless it’s a habitable room above it. 
as far as I’m aware. 

[Moonshine]

34 minutes ago, saveasteading said:

Good question. The building regs may imply yes. The reality is it won't burn down until the rest is already gone. 

 

Could the same not be said for steel structural support, in this case could be a steel ridge beam,l. If it was steel it would need to be encased in fire board.

 

It seems strange to me that a timber structural support that can ignite isn't required to be protected in the same way.

[George]

21 minutes ago, saveasteading said:

Good question. The building regs may imply yes. The reality is it won't burn down until the rest is already gone. 

Don't need to protect roof structural elements in normal two storey house.

 

Beam span is quite large so agree unless you put in a deeper beam then it is about right. I note it isn't a simple pitched roof, there is a flat section so something else is going on which might explain the size. They've also allowed for a splice which may help installation.

 

Glulam is an option but end up being pretty big over 6m or so.

[Moonshine]

2 minutes ago, Russell griffiths said:

Not unless it’s a habitable room above it. 
as far as I’m aware. 

 

That must be the nuance that i am missing 

[George]

I should add, builders always say it's a big beam. They are designed on deflection, not strength. This is particularly important for vaulted roofs because deflection at the ridge manifests as an outward thrust at the wall plate, which is particularly not good for masonry.

[Russell griffiths]

@NandM

why are you bothered and why are you questioning it. 
my point. 
unless the beam in question is made of unobtainiam and it’s a cost point you are arguing then. 
 

you will need some sort of beam, that’s a definite 

a timber kerto beam or laminated gluelam will not be cheaper than a steel beam. 
whatever  you use you won’t be picking it up by hand, so it’s a telehandler or a crane, that’s for sure. 
 

the only thing I can see in your drawing that I think is pointless is the splice joint, a 10m beam can be made in one piece, it can be delivered on a normal truck, it doesn’t require an artic, so unless you are really tight for space I see no reason to make it in two parts. 
a splice joint could add £250-400 depending on number of holes and bolts used. 
 

all I would say is if you can go deeper with the size it could get lighter, maybe 45-55 kg a metre, so it ends up 500kg instead of 900kg. 
still needs a crane or a forklift though. 

[saveasteading]

1 hour ago, Moonshine said:

Could the same not be said for steel structural support

Yes. At a certain chunkiness they don't need any (or partial) protection. The one here for example is unlikely to need any.

There is no occupation above it.

At 300+ degrees it will soften a bit. 

 

@NandM Re the  splice, and the rest, Russell is right. Ask the supplier for 2 options, in case it happens to suit manufacture or delivery costs (small lorry)

But lift it in one piece.

 

If the builder hasn't seen beams this heavy, he either hasn't much experience of beams....or some cash and no regulations clients have unstable houses.  Either way, discuss the proposed method for lifting and fixing it.....a 'risk assessment'.

[NandM]

@Russell griffiths - I wanted to see if we could get to a size/weight that could be manhandled and avoid the expense of a crane. If the beam sizing seems fine, then a crane would be needed whether spliced or not....which would then bring to the question of the point of the splice if I was to crane it in. I didn't realise spliced joint would add that much cost....it now makes sense why I had one fabricator suggest seven splices "as that's how lots of lofts are done". 

 

Good point re manufacturer delivery @saveasteading - I'll keep that in mind and ask for two quotes.

[NandM]

Re deeper ridge beam, it looks like the current height is around 2.8m, so I could loose 20cm and still have a very decent head height.  I'll explore this with the SE as well.

[Russell griffiths]

Regarding splice cost. 
I haven’t a clue about current costs, but basically they charge by the hole, so a plate with 6 holes in both sides would be 12 holes @ £10 a hole ( just a guess) plus the two or 4 steel plates. 
 

Regarding lifting it

in one piece your beam is 854kg

in two it’s 427 kg. 
in three it’s 284kg. 
so cutting it in 3 it’s still over a quarter of a tonne. 
 

if I was on a budget and doing it myself I would lift them up through the first floor and then get them up to the final point. 
however if you are paying a builder and his two lads to do this the time you have payed out £450-600 for a day of messing about you could have paid to have it lifted up mechanically and been finished by 11am. 
 

it’s all a bit of save a quid in one hand and pay it out in another. 
 

if I was doing this I would look for a local company with either a large hijab lorry or a mobile tracked crane. 

[LiamJones]

Have a look at spider cranes. I just paid £350 for half a days lifting a 11m ridge beam, 2 posts to sit it on and a ground floor steel. 5 pieces in total. Don’t mess around trying to do it by hand, your brickies are far slower, so will work out way more expensive and more risky. 

[Gus Potter]

13 hours ago, NandM said:

My SE has spec'd a fairly hefty ridge beam for a 9.6m span @ 254x254x89UC. This will be supporting either 9x2 or 10x2 rafters with clay roof tiles and in-roof solar.

 

A couple of builders I've had over were surprised by the size of the beam and the challenge of getting it up.

Good question to ask. My own view is that it is healthy for your builders to query the design and I can see why they / et al ask as using a column (UC) section as opposed to deeper and narrower universal beam section (UB) immmediatly flags up.. why is the SE doing this?

 

It is a long span and other posters are making suggestions as to alternatives. But I'll go with your SE and that makes me think.. why the UC or not say Glulam etc. I suspect that at the top of your stairs you need 2.0 m head clearance and the SE has struggled to get the structure to fit within the Achitectect's envelope that is available for structural members while maintaining BC compliance. Thus to make the structure work within the given envelope the SE has had to use a UC section that is inherantly less efficient for this application in terms of steel weight and assocaited conection cost. 

 

You'll see on the drawing you posted that there is a splice in the beam stated at 1/3 point.

 

At 1/3 points there is often still a fair bit of bending force in the beam and that can add to the connection fabrication cost. I try and go for 1/4 in for the end splice as the bending forces are less and can simplify the bulkiness / cost of the connection.

 

Now I mentioned the connection cost. If the connection requires a full strength weld (full pen butt weld) then some smaller fabricators need to get an inspector in to check the full pen weld .. this can add £300- 500 quid to the cost of the steel on a bad day! Or you can go to a larger fabricator who may get the inspector in at a lower rate or have in house staff who can do it.. but you pay for that in house service.. So you need to ask the question can we go for a 1/4 splice (with simple fillet welds) and also ask the Contactor if they can lift a 3/4  length beam instead of a 2/3 length beam. If so what is the steel price now?

 

Sometimes DIY / BH folk get a steel price and wonder what the difference is.. it can be just down to a connection and the way it is specified / welded up on a small domestic project!

 

 

 

 

 

 

 

 

 

[Bonner]

Can’t you get this size beam in one piece if you are lifting it mechanically? I got a 10m length of 203x102.

[Conor]

18 hours ago, Moonshine said:

 

That must be the nuance that i am missing 

Structural elements need to be protected from fire if they are supporting a habitable area or an escape route. A roof ridge beam does neither of these, so does not need protecting whether timber or steel. I think some over zealous BCOs insist on this applying to roof structures.

[NandM]

9 hours ago, Gus Potter said:

Good question to ask. My own view is that it is healthy for your builders to query the design and I can see why they / et al ask as using a column (UC) section as opposed to deeper and narrower universal beam section (UB) immmediatly flags up.. why is the SE doing this?

 

 

Thanks @Gus Potter - this bit had me looking at all the other beams for the extension and they are all UC. I'll ask the SE why the choice of UC over UB.

 

As we'll be having a new roof structure put in, then it feels like going for the one piece and paying for the craning service makes the most sense. As @Russell griffiths says, it'll probably work out the same cost wise and be quicker. 

[cwr]

Out of curiosity I asked my SE why he'd spec'd a UC for a horizontal beam and not a deeper lighter UB. He said due to torsional buckling. Slightly different situation as was supporting a wall, but no doubt you SE will have a justification for the choice.