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Over on eBuild I was talking to an SE type guy about him doing some calcs for me so I could install some strengthening steels in my garage roof to make a bit of a storage area up there. I've had a look but can't find the thread nor access any PMs. 

 

Anyone on here remember who it was?

 

Cheers

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17 minutes ago, Construction Channel said:

tony51 possibly, he did my calls for me. i can give you his email if it is who you are looking for?

 

 

Could have been.....tbh can't remember! 

 

If he won't mind then please PM me his email.

 

Cheers 

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I emailed him but he's not come back to me.....

Edited by Onoff

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After a trawl through what's left of eBuild I see the guy I was talking to went by the username "structuraldesigner". I can't access any PMs over there so can't even see if I had contact details for him. Anyone know the chap?

 

Cheers

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PM me the drawings and I can have a look 

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1 minute ago, PeterW said:

PM me the drawings and I can have a look 

 

Thanks very much. AutoCAD .dwg file OK?

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PDF may be quicker as I can look on the train 

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Having a bit of time to kill I'm looking to resurrect my plan to put some storage space in the currently truss raftered roof. Just found my old sketches and re-did the CAD.

 

Trusses are made out of nom. 70x35 timbers. There's a 178 x 102 RSJ spanning the front opening top of which is 80mm lower than the u'side of the trusses. Construction is 4" Celcon blocks with pillars. Gable end is 4" Celcon carried on up to the peak (some pillars on that wall too that I should add. The end where the trusses aren't shown is a hip end.

 

One "plan" is to span some deep (thus expensive) timbers across and sister them to the trusses. Then build up a frame inside and cut out the trusses to give a clear storage area. 

 

Another option was to install a new steel, front to back from the middle of that RSJ and support it on a post at the gable end. Ideally I don't want any other vertical posts along it's length to open car doors into etc. Or maybe steel goal posts tucked tight to the side walls, again with a central steel.

 

Whatever option it'll be without taking the existing roof felt & tiles off.

 

Any thoughts, pointers? Getting an SE in, not going to happen! 

 

garage_001.thumb.JPG.f5b8748557b8bbb6691973e397a7a47a.JPG

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I had an SE design something similar for the attic in our current house. Sistered joists and rafters, plus plywood gussets at the ridge. That let me remove the central ^.

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@scottishjohn, continuing here from the other thread:

 

I have a double garage with truss rafters. I desperately need more storage space. I've been up in there and measured the section of the trusses, nominally 70x35mm.

 

garage_005.JPG.6da938bd65dd07840a038fe4c7adfd63.JPG

 

Across the front entrance is a 178x102 RSJ (as in tapered flanges). I'd thought about just spanning the walls with bfo timbers, say 9"x3". I've an old Approved Document A here from 1985 and even 225x75 SC3 at 600 centres doesn't cut it as floor joists. Again, this will not be a "living" area, just storage.

 

Thus half a plan then to run a new UB down the centre, mid span and underneath of the existing trusses. I've drawn this in as a 254x146x31kg/m as it fits with just 7mm of packing between it and the u/side of the existing trusses. Connect the UB to the RSJ at the front. I imagine I'll need square posts coming up from the floor to support the new UB. Then span wall to wall, on the existing wall plate with 200x47. Then frame out up and over in 150x47, screwed to the existing trusses. Then CUT AWAY the existing trusses giving me an open "room".

 

garage_006.thumb.JPG.1f46afb1010a1c8d361bd4258c876dce.JPG

 

garage_007.thumb.JPG.7f86a00b794ff1a7c949697cc3238048.JPG

 

I'll cost it versus a new timber roof trusses.

 

If money were no object! 

Edited by Onoff

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that will work for sure -

If you made the black frame work out of large enough wood ,then no need fro the longditudinal RSJ

  would just shadow the original trusses with larger ones and fix together

then a cross brace close to the apex along with larger lower cross beam  it will be fine --verticals if you like to make it stronger and have fixing for walls of upper room

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3 hours ago, scottishjohn said:

that will work for sure -

If you made the black frame work out of large enough wood ,then no need fro the longditudinal RSJ

  would just shadow the original trusses with larger ones and fix together

then a cross brace close to the apex along with larger lower cross beam  it will be fine --verticals if you like to make it stronger and have fixing for walls of upper room

 

It'll work in essence but I'd like to be a bit more scientific about it. I'm all rule of thumb generally!

 

My new, proposed ceiling horizontal joists. Do I consider them Floor Joists or Ceiling Joists for a start?

 

Now for Floor Joists there are 3 dead load options:

 

- Not more than 0.25kN/m2

- More than 0.25 but not more than 0.50kN/M2

- More than 0.50kN/M2 but not more than 1.25kN/M2

 

But for Ceiling Joists only two options:

 

- Not more than 0.25kN/m2

- More than 0.25 but not more than 0.50kN/M2

 

In each case 3 joist spacings; 400, 450 & 600mm. In my case I've assumed 600mm though it varies from 440 to 645mm. Not one pair of trusses is centred the same.

 

Assuming Ceiling Joists then: Taking SC3 tables as it was, now C16 I believe. Not more than 0.25kN/M2 is 250kg over an area of 1 square metre. I'd never exceed that. A 225x50 joist allows a maximum clear span of 5280mm.

 

I've a clear span between my walls of 5860mm.

 

(For Floor Joists a 225x75 only does 4880mm at 600mm centres).

 

 

 

 

 

 

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5 minutes ago, Onoff said:

 

It'll work in essence but I'd like to be a bit more scientific about it. I'm all rule of thumb generally!

 

My new, proposed ceiling horizontal joists. Do I consider them Floor Joists or Ceiling Joists for a start?

 

Now for Floor Joists there are 3 dead load options:

 

- Not more than 0.25kN/m2

- More than 0.25 but not more than 0.50kN/M2

- More than 0.50kN/M2 but not more than 1.25kN/M2

 

But for Ceiling Joists only two options:

 

- Not more than 0.25kN/m2

- More than 0.25 but not more than 0.50kN/M2

 

In each case 3 joist spacings; 400, 450 & 600mm. In my case I've assumed 600mm though it varies from 440 to 645mm. Not one pair of trusses is centred the same.

 

Assuming Ceiling Joists then: Taking SC3 tables as it was, now C16 I believe. Not more than 0.25kN/M2 is 250kg over an area of 1 square metre. I'd never exceed that. A 225x50 joist allows a maximum clear span of 5280mm.

 

I've a clear span between my walls of 5860mm.

 

(For Floor Joists a 225x75 only does 4880mm at 600mm centres).

 

 

 

 

 

 

they are not only floor +ceiling joists but also roof trusses -if you fit your vertical ones as shown in picture-as they are taking downwards load from roof ,unless you make the "sister trusses  big enough to take all roof + a bit 

leaving originals inplace and fixing to them  I am guessing would make them plenty strong-that of course is a guess on my part- I am  not an SE

 you could of ocurse cross brce the sections outside the verticals you are using as walls for top room

you would end up with four triangles then with the small top brace up nearthe apex

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Clive, I'll PM you the SE's notes for our conversion- don't want to put them online in case of copyright issues

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@dpmiller, received with thanks that info. As per my pm it appears yours was a truss rafter roof in a house to start off with therefore beefier than the lightweight ones in what is a garage by design. Saying that your clear span is a little more.

 

I'd hoped to make contact with a tame SE mate in NZ to calc it up for me. I want to start pricing things up timber wise (or steel if necessary) but a bit stumped without someone casting their eye over it. I can draw what I THINK will be structurally sound but there'll always be that nagging doubt without proper advice. The other option is I go OTT but I wonder how much I will have needlessly spent going that route!

 

I know there's Woodexpress which is superb but pricey. The demo version is good but only goes up to 5250mm span.

 

http://www.runet-software.com/WOODexpress.htm

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Flitch beams...I never knew they were called that!

 

Wondering if x2 9"x3"s sistered, with a steel plate inbetween would span 5860/6060mm and negate the need for supporting steels. I came across this flitch beam calculator. Worth spending £20?

 

https://www.yourspreadsheets.co.uk/flitch-beam-design-to-bs-5268.html

Edited by Onoff

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16 hours ago, Onoff said:

Flitch beams...I never knew they were called that!

Did you call them felch by mistake.

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1 hour ago, SteamyTea said:

Did you call them felch by mistake.

 

Armageddon!

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22 hours ago, Onoff said:

Flitch beams...I never knew they were called that!

 

Wondering if x2 9"x3"s sistered, with a steel plate inbetween would span 5860/6060mm and negate the need for supporting steels. I came across this flitch beam calculator. Worth spending £20?

 

https://www.yourspreadsheets.co.uk/flitch-beam-design-to-bs-5268.html

I did 6.1m with SE sign off for an attic conversion, and that was with the flitch, and that was taking the head of the stairs as well. Done in 7x2, sistered, plus steel fillet, drilled and bolted every 400 IIRC. Stronger than a strong thing, like near zero deflection, and the first time I'd heard of them too. Then used the same principal to reduce the profile of the huge 12" purlins down to 5" flitch. HELL of a lot easier to get up 3 stories vs steels, which would have had to have been done in sections, plated, and bolted up. Hired a Mag drill for the day, and it made drilling a breeze. 

3 man job at that length as that steel will twist, flip and fly out of your hands quick-as, and good luck trying to stop it in mid-air. 

Edited by Nickfromwales
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1 minute ago, Nickfromwales said:

I did 6.1m with SE sign off for an attic conversion, and that was with the flitch, and that was taking the head of the starirs as well. Done in 7x2, sistered, plus steel fillet, drilled and bolted every 400 IIRC. Stronger than a strong thing, like near zero deflection, and the first time I'd heard of them too. Then used the same principal to reduce the profile of the huge 12" purlins down to 5" flitch. HELL of a lot easier to get up 3 stories vs steels, which would have had to have been done in sections, plated, and bolted up. Hired a Mag drill for the day, and it made drilling a breeze. 

3 man job at that length as that steel will twist, flip and fly out of your hands quick-as, and good luck trying to stop it in mid-air. 

 

Ta. What centres?

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38 minutes ago, Onoff said:

 

Ta. What centres?

What centres, what?

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1 hour ago, Nickfromwales said:

What centres, what?

 

400, 450, 600 centres? Flitch beam spacing or was there just the one?

 

I'd need up to 9 such beams:

 

garage_001.JPG

 

Just realised there is/are flitch beams in this house now. Didn't put two and two together! I've the dormer extension drawings that I got (as a freebie) from BC a couple of years back.

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You don’t use the FB’s throughout!

One steel across the garage door opening, one FB mid span, parallel to the steel, a wall plate on the back wall, and then timbers stitched in between. 
Looking at the pic, why not just use steel  to form a T and then span from centre out?

 

However.........

 

As we are in fear of over-engineering this ( 🤏 ) why not revert to the earlier suggestion of a 5x2 each side of the bottom of the trusses? So bloody simple, and if you’re going to board out and form I deck you there, glued and screwed, it’ll be rock solid. 
 

Every time I do structural joinery I look at it and think to myself “that’s way over the top”, but get an SE involved and that’s what usually happens ( as they have to professionally underwrite that solution ) so do you really need this degree of technicality for this project ?

 

Edited by Nickfromwales

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