Please Guide my Build!

[hmpmarketing]

12 minutes ago, Nickfromwales said:

What will support the steel and stop the cold bridge with that being end-exposed? Plate it and 'gallows bracket' it? Will need to be an UC then and not an UB?

 

Something I asked above, Steel spline sitting or inbuilt into blockwork?

[Nickfromwales]

11 minutes ago, hmpmarketing said:

 

Something I asked above, Steel spline sitting or inbuilt into blockwork?

Yes, saw that but it can only be both, eg inbuilt would be sitting on the last course of block. As its a flat roof, you may be able to detail some cold bridge mitigation in but it would be negligible / useless. "Attached" is the other option where the steel is mechanically fixed to the block. 

 

EWI may help, and allow you to go cheaper on the block. 

[hmpmarketing]

5 minutes ago, Nickfromwales said:

Yes, saw that but it can only be both, eg inbuilt would be sitting on the last course of block. As its a flat roof, you may be able to detail some cold bridge mitigation in but it would be negligible / useless. "Attached" is the other option where the steel is mechanically fixed to the block. 

 

EWI may help, and allow you to go cheaper on the block. 

 

I suppose the steel beam can be designed in a way that it can be attached to the blockwork by some type of screws? so it is flush with the blockwork and the timber joists sit properly on top.

 

I would prefer only internal insulation, less work to do as brickie would only have to render the blockwork

Edited August 14, 2018 by hmpmarketing

[Nickfromwales]

6 hours ago, hmpmarketing said:

in a way that it can be attached to the blockwork by some type of screws?

That would have to be a plate with a welded flange, pre drilled to accept the wall fixings and the steel ends. Do-able, but more cost / complexity. 

 

6 hours ago, hmpmarketing said:

and the timber joists sit properly on top.

Id rather plate the steel with timber and butt the joists up to that so the timber sits flush with the steel, that way there is no boxed-in beam showing underneath the ceiling level.

[PeterW]

1 hour ago, Nickfromwales said:

That would have to be a plate with a welded flange, pre drilled to accept the wall fixings and the steel ends. Do-able, but more cost / complexity. 

 

Id rather plate the steel with timber and butt the joists up to that so the timber sits flush with the steel, that way there is no boxed-in beam showing underneath the ceiling level.

 

Only issue with plating a beam in a flat roof is the monumental cold bridge it creates unless you build a flat roof with all the insulation on top of the deck. 

 

For ease and speed I would use 140mm blocks but put a block on edge in the middle of each front and back run and make a short pillar and then drop the steel on that. It can be sloped front to back easily enough and the joists run left to right. Canilevering the front overhang wouldn’t be a problem. 

[Nickfromwales]

Ah, yes. 2 heads better than one. 

Maybe better with a trio of 9x2's, joints staggered, and make a flitch beam. Best of both worlds ( timber faced already ) and then sit the firing pieces on top going perpendicular to the steel plates in the flitch to reduce the cold bridge. All depends if pillars are preferable or not, but pillars and a regular steel with the joists / firing pieces atop is probably the cheapest and quickest route.

I'm pre-programmed to eliminate pillars and boxed in beams as I massively dislike both. OCD sorry. 

[PeterW]

You could lose the pillar in the wall as it would poke out 75mm and then the steel or timber would sit on it and then infil the gaps with insulation and over the top with 25mm all round...?

[hmpmarketing]

Good morning folks!

 

@PeterW and @Nickfromwales not a fan of pillars ?

 

flitch beam eh? one learns something new everyday! Never heard of this until you wrote and took a quick look on the web. Is it a beam that is made of “sandwiched” steel and timber as the outer face? Is this to eliminate the cold bridge issue?

 

(this is from a company not too far from me)

 

I went to bed yesterday and could not even watch a proper movie without thinking about this and reading up.

 

Also, I came up with an alternative option for the warm flat roof: to sit 100mm thick or thicker SIPs panels on the top  of walls / beam instead of going with the composition of the flat roof being:

 

Joists

osb decking (18mm)

insulation 100mm

os decking (11mm)

EDPM finish

Edited August 15, 2018 by hmpmarketing

[PeterW]

Remember that mantra ...??

 

Thin Cheap Warm - pick two..??

 

That roof is heading the same way ..!! Sips are not cheap ...

[hmpmarketing]

1 minute ago, PeterW said:

Remember that mantra ...??

 

Thin Cheap Warm - pick two..??

 

That roof is heading the same way ..!! Sips are not cheap ...

 

Hi @PeterW yea, completely agree.

 

I have just made some quick numbers:

 

To cover the roof area + overhangs I would need about 20 panels 1200mm wide by 3000mm @ £125 each, splines are a tenner each, so looking at about £2700 or so, was just thinking if it would make it easier with the beam, I would probably need 2 now hehe

 

Any idea how much a steel/flitch beam would cost?

[PeterW]

So whatever you do there you will need at least two steels if you go SIPs and steels at 8m long are big and expensive....

 

If you want to save cost and do more DIY then look at reducing the size to use standard sizes of product - if you went the SIP route from memory they make them in 6m lengths so you could potentially use these off the shelf assuming they meet the span requirements without central support. 

 

The other radical option would be to split the building into a pair of 4x3m blocks with a spine wall and then everything becomes standard - you can put a pair of double doors or just an opening between the two rooms but it would allow flexibility later 

 

 

[hmpmarketing]

2 minutes ago, PeterW said:

So whatever you do there you will need at least two steels if you go SIPs and steels at 8m long are big and expensive....

 

If you want to save cost and do more DIY then look at reducing the size to use standard sizes of product - if you went the SIP route from memory they make them in 6m lengths so you could potentially use these off the shelf assuming they meet the span requirements without central support. 

 

 

Yea, looking at the costs, SIPs are coming up too costly, I rather have fun doing the sandwiched warm roof myself.

 

Someone emailed me now regarding engineered i-joists, waiting for the quotation on that, if I use them this would eliminate the need for the steel beam too

 

5 minutes ago, PeterW said:

The other radical option would be to split the building into a pair of 4x3m blocks with a spine wall and then everything becomes standard - you can put a pair of double doors or just an opening between the two rooms but it would allow flexibility later 

 

I really need that "open plan" for the bigger room, since I plan to set up a drum set, guitar, etc....

[hmpmarketing]

 

So right now this is the idea for the flat roof joists (joists 47mm x 220mm max span 4.91m) + steel/flitch beam, 400mm spacing, looks good?

Edited August 15, 2018 by hmpmarketing

[Nickfromwales]

A manufactured flitch would look nice cleaned up and stained eg left on display.  . 

[hmpmarketing]

4 minutes ago, Nickfromwales said:

A manufactured flitch would look nice cleaned up and stained eg left on display.  . 

 

I did think about that....but if the beam is in-built into blockwork and flush, plasterboard would be attached to the joists (to create a service void, say for in-ceiling lights) so it would be covered up ?

 

EDIT: what the hell am I talking about it!, please ignore @Nickfromwales

 

Edited August 15, 2018 by hmpmarketing

[Nickfromwales]

For the joists to stop / start over the flitch you'd need a 8x3" joist above the flitch ( running in line with it ) and the timber ends would need to be mechanically fixed to the extra joist. You'd then have to noggin between the ceiling joists near to the beam to keep things true. 

[Nickfromwales]

You'd have a deep void between joists for lights ! Keep the ceiling high IMO. 

 

[hmpmarketing]

7 minutes ago, Nickfromwales said:

You'd have a deep void between joists for lights ! Keep the ceiling high IMO. 

 

 Sounds interesting, just trying to understand the joist ends that meet the left/righ walls would need to be raised too (another 8x3 running along the wall line)?

[Nickfromwales]

Raised ? What for ?

[hmpmarketing]

maybe Im misunderstanding.... so the flitch/beam would not be flush to the wall, but the 8x3 joist above?

 

Edited August 15, 2018 by hmpmarketing

[Declan52]

Would it not be nicer looking if the joists where in the web of a steel beam on each side so you end up with a totally flat ceiling.

[Nickfromwales]

47 minutes ago, Declan52 said:

Would it not be nicer looking if the joists where in the web of a steel beam on each side so you end up with a totally flat ceiling.

Already suggested but issues with the cold bridge unless a lot of insulation goes over it.

[hmpmarketing]

1 minute ago, Nickfromwales said:

Already suggested but issues with the cold bridge unless a lot of insulation goes over it.

 

So @Nickfromwales my drawing above is exactly what you suggested with the 8x3?

[Nickfromwales]

1 hour ago, hmpmarketing said:

maybe Im misunderstanding.... so the flitch/beam would not be flush to the wall, but the 8x3 joist above?

 

 

Ok. 

Your pic shows 2x 4m timbers making up the 8m span. That I assume means your showing the break in the run on top of the 6m steel ? You cannot have the break there unless the joints are mechanically fortified. Regs will ask for a certain distance for the joists to sit on the steel so the ends on the joists don't compress under the weight. 

The 8x3" would be in the middle of the steel, sat on top, running along its length and positioned vertically. The joists would then be made off into joist hangers affixed to the 8x3. 

Clear as mud ? I'll do a pic if your not sure. 

[Declan52]

7 minutes ago, Nickfromwales said:

Already suggested but issues with the cold bridge unless a lot of insulation goes over it.

Fully fill the joists with Rockwool and then overlay with OSB and 100/150mm of pir then whatever covering is being proposed.