Steel work and stud wall-lifes too short.

[meadowhog]

I have secumed to asking on this great forum for help. I am a year into my solo extension and know that it takes me just as long to do the research as it does to do the job I built a fish pond once!

An answer to 3 Qs would take a weight of my mind.
1: Im fitting wet underfloor heating and simply want to know if the internal stud walls should be built off the slab, off the insulation, off the screed or off a shuttered concrete raised area on the slab?

2:Im putting in floor to roof UPVC windows and realise that a steel support needs to go above the patio doors. This is to support the windows above. The glazing guy says fit the smallest rsj available. At 125mm I think there may be a smaller section will do? Or is there a better solution to reduce this height?

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• meadowhog
• 22 Jun 2009
• 2

3:Im taking out the old patio doors and concrete lintel. Then fitting a steel above the old wallplate and below the new rafter ends. Then hanging the old wall plate. My problem is how do I support the steel at each end? Can I cut a section out of the old wall plate to enable a padstone to sit on the wall?

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• meadowhog
• 22 Jun 2009
• 1

Hopefully my life expectancy willbe extended!

 

[noseall]

What is that building, a barn?

 

[meadowhog]

Im beginning to think its a Mausoleum. That made my week.

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• meadowhog
• 22 Jun 2009
• 1

 

[noseall]

Are they padstones beneath the purlin ends and have you had to hack back the purlin/plate overhang for fear of interfering with the barge soffit?

What size is that mid-span pier beneath the purlins?

 

[The-brickie]

In answer to (2) what about curtain walling?

And (3) Yes

 

[meadowhog]

Thanks Guys,
Yes they are spec'd padstones with rsj purlin and plate. And yes I did cut them at an angle (bought a new saw) and built ladder ontop. I could have saved the hastle but wasnt sure if the ladder would sag before I got the gable closed. (Im a bit slow).

Each Pier is 675 x 225. I built them to structural eng calcs.

Curtain walling is a great idea. I'll try and find a bit. The steel support over raised opening was bugging me, thanks.

 

[freddiemercurystwin]

Curtain walling still requires a degree of support/wind loading resistance.

 

[andywc]

grief

i see what you mean nose... that's a way slender column!

and i can't really make out the bearing of the purlin on the padstone, perhaps there's a pier behind

and while there are purlins i'm not sure how roof spread is being resisted

be good to have some more pictures

 

[Shytalkz]

Nah, that pier's ok.

No spread: purlin vertical, rafter birdbeaked over.

Not sure what purpose that tie rod is serving though....(none!)

 

[andywc]

hi shytalk

when i get some time i'll look at a calc for that column; makes me shudder at its slenderness

spread; i understand what you're saying but the glulam is very slender too and of course we've no support to the ridge; at least the tie bars between the glulams may prevent some distortion/separation/spread...

notice there also seem to be diagonal ties too...

 

[Shytalkz]

Glulam? That's a steely beam 203x102 or 133, with a plate on the top

Pier is about 3075 high, min dim is 215, hence slenderness is 14.3, waaay < than 27. I reckon it's blocks laid-on-side, one and a half long, so dim the other way is 670. With nominal eccentricity in the plane of the beam and none across the pier width, I reckon the allowable ULS load is c 110kN say 65kN SLS. That's not going anywhere.

If the rafters are birdbeaked at purlin and plate, the only lateral thrust left out of balance is from ridge to purlin. That won't go and spread itself, unless the beam deflects significantly. Not going to happen.

The use of rods as diagonal bracing to the roof is erm interesting: the position of the veluxes down the other end preclude the use of such in the opposite direction, so it will work with the wind sucking on the nearest gable, but not blowing on it. Hope the wind down there is uni-directional .

And I bet the wall panels either side of the gable opening don't work with wind on them, either....

 

[andywc]

hi shytalk

we're assuming that hef = 1h and therefore that the column is laterally restrained...

rather than hef = 2h where there is no lateral restraint at the top of the column... the ladder doesn't count!!

shudder

 

[Shytalkz]

Ah, but you see I would take the roof as being - taiap - a rigid diaphragm, thus restraining it across the plane of the purlin...it's not the same as, say a pier with steelies like this, on top of which is a wall with nothing coming in from the sides at beam level - now that would be laterally unrestrained.

You'd be happier if the pier was rotated through 90° wouldn't you...?!

That set up is tighter than a nun's chuff, regardless of the numbers on the piece of paper.

Personally, I'd have used a steel post there, much less xsa and consequently less impinging on the circulation space in that room. And far less ugly too. That layout looks like something that has been SE-led, rather than architect-led; always a bad thing for us straight line merchants .

 

[andywc]

but is it a rigid diaphragm; that's a big assumption...

i'd be happier if it wasn't so slender, which ever way around it goes

could have used a steel post, it would be smaller than a non-slender masonry column and the slender masonry column there right now

 

[Shytalkz]

Engineering judgement

Post was deffo the answer though. Musta bin an IEng who did the design...