Fitting hand rails to a flat roof

[i_am_fubar]

I am trying to work out the best way to fit hand rails that actually comply to building regs strength requirements THROUGH the deck of a new, EPDM covered flat roof. I am currently at this design, the calcs show that the steel comonents won't fail under test loads.

Can anyone offer a sanity check on the design?

Untitled

• i_am_fubar
• 8 Jul 2013
• 1

(Drawing not to scale)

Joists are 220x47 (3.8m span).

The post will be 50x50x3 box section steel welded to a 6mm thick plate. The studs (shown as countersunk screws) will be welded into place and ground so the top of the plate is smooth.

There will be 4 studs through the deck for each plate. And 3 studs going through the joists between the angles.

The plate will be welded to match the fall of the roof so that the posts are vertical when bolted down.

Silicone (or other sealant) will be used between the plate and the EPDM deck cover, a second piece of EPDM will be bonded over the plate to provide additional waterproofing.

Nylock nuts or shakeproof washers will be used to prevent nuts vibrating loose from foot traffic.

Along the sides of the roof, this arrangment will be attached to noggins rather than the joist to maintain load charactaristics.

All input welcome.

Cheers,
Fubar.

 

[i_am_fubar]

Is this perhaps something I should move to the roofing section rather than building?

Fubar.

 

[catlad]

Looks ok to me but you are going to need a few noggins to stop the joist turning over especially if there is more than one post on a joist, you would probably be better with a post bracket that spans more than one joist

 

[freddiemercurystwin]

That detail is destined to fail, it needs a cowl and the membrane dressed up the railing post.

Untitled

• freddiemercurystwin
• 27 May 2010
• 4

Untitled

• freddiemercurystwin
• 28 May 2010
• 2

All structural issues aside.

 

[i_am_fubar]

Cheers guys.

Ok, so extend the membrane flashing up the post and then cowl over. Makes sense.

If I were to go with my proposed plan, would the EPDM be allowable under the fixing plate, or would it have to be plate to deck directly?

For the flange / seal, would UV stabilised adhesive lined heat shrink be acceptable (posts to be stainless steel), or would it have to be a rigidly formed unit attached to the post?

Catlad, which way do you think the turning moment would be applied? It will surely always be in the same plane as the joist direction, rather than as a twisting action of it's length.

Would an EPDM pipe boot work instead of the protec membrane?

Freddy, what structural issues do you foresee with that design?

Is that top diagram showing a steel pipe welded to a plate that is then bolted to the joist? I like it. Though would it have to be a double joist? I imagine the dependant strength of the joist(s) would be proportional to how many posts you had per meter of railing.

Also, would that be fitted to a noggin when the railings are in-line along the length of a joist, or continuing along the joist?

Cheers,
Fubar.

 

[dilly]

The drawings are for a liquid system,far more flexible than epdm,you need to speak to a technical support from the epdm suppliers.

 

[i_am_fubar]

By flexable, I assume you mean options to install, rather than physical flexability of the material?

I was told to look at polyroof, is it suitable for DIY installation?

For EPDM, there are boots such as these: http://www.portalsplus.com/products/small-pipe-boot

Which I'm sure would suffice for sealing. Though I would still be tempted to put some sort of weather flange over it.

Fubar.

 

[catlad]

If you are going to attach those post to your joists like in your diagram then its possible to twist your joist with the right amount of force, and maybe crack your plaster board underneath so it might be an idea to sheath the ceiling in ply before re- plaster boarding.

 

[i_am_fubar]

Ahhh, I see the ambiguity in my picture. Forces would be applied towards and away from the screen. Rather than left to right.

So aside from the bolt splitting the wood, the joist would need to lift up rather than roll over to fail.

Fubar.

 

[freddiemercurystwin]

The drawings are for a liquid system,far more flexible than epdm,you need to speak to a technical support from the epdm suppliers.

They are but the principle is identical. The membrane is dressed up the post.

fubar, the turning force exerted on a handrail at the base is colossal, at worse as mentioned it will fail completely splitting joists and plasterboard cracking etc, even a bit too much movement and the waterproof junction will fail. You would be surprised at how an engineer would specify fixing handrails to a flatty.

 

[^woody^]

Why can't these be fitted to the perimeter walls

 

[i_am_fubar]

Reasons for railing on the roof rather than to the wall are primarily aesthetics, to keep the outward appearance the same. Don't really want to go through the hassle of PP.

Secondary reason is that due to a large area of windows and doors close to the roof (only 3 courses of bricks above them) There isn't enough structrual meat to hold them. A wall would just pull apart.

Freddy, I'm an electromechanical engineer by trade and work with a lot of masts. THEY have colossal turning moments. Hand rails just have big ones. The figures from my more detailed drawing put the tensile forces on the through deck bolts at 11kN, easily within the allowable loads for the steel components. The only unknown is the timber. while it'll be standardised as C16, the very nature of natural materials makes the required splitting forces an estimate only.

The advantage that I saw in my design was that the joist would be clamped and loaded equally from both sides, resisting the bolt twist exerted by a plate only attached to one side. Giving more equal loading though the fixing holes.

Of cause no structure will be totally ridged (and nor should it be). But it was my understanding that EPDM, due to it's rubber composition, would accommodate a reasonable amount of movement without leaking?

Ta all

Fubar.

 

[^woody^]

. Don't really want to go through the hassle of PP.

What makes you think that the two methods are treated differently in terms of planning regulations?

I can't see how a well designed perimeter balustrade will look any worse than your alternative

 

[i_am_fubar]

While I'm still trying to find the details of the planning application that was surrounding the railings, the searches returned by our conveyancer titles the planning application as 'Fitting of iron railings onto the roof'. There may be stipulations in it for mounting (or lack there of) as well as appearance (iron, rather than st/st or glass).

But sufficed to say, the lack of available mounting locations is really the killer for side mounting. Plus, there is having to deal with the gutter.

 

[Anthony Oliver]

Hello Fubar, I realise that your thread is quite old but I'm trying to achieve the same end. Did you conclude the project and if so what solution did you use? Thanks