Firestone DPMD with Balustrade

[Ydraiggoch]

Hi,

Has anyone come across this issue before? If so would you mind sharing your solution?

So, I am having a Flat roof / Balcony built as part of some ongoing extension works. The intention is to lay Firestone as the roof membrane and then lay a floating Deck on top. But as this is a Balcony I will obviously need to install Balustrade. I plan to install the standard SS Posts with Glass Sections.

My problem is, how do I install the Base plate for the Posts without voiding the warranty of the Firestone. The Roofers suggest installing the base plate under the membrane and have the post slotting over the top. This option would be fine, but I think it might look a mess, it increases the risk of the balustrade not fitting when I come to install the Posts / Glass, and if I wanted / needed to replace a Baseplate I would have to rip up the membrane.

The other option which the Builder / Joiner suggests is to install ontop of the membrane, and bolt through it Voiding the warranty, but ensuring plenty of Silicone sealant is applied. This would be my preferred option, but not keen on deliberately voiding the warranty.

My opinion is that this can't be the first time anyone has come across this issue, and am surprised that my roofer only has one suggestion! So, I am hoping the experience on this site might be able to help???

Many Thanks in advance!

 

[freddiemercurystwin]

The baseplate must go down to the structure in accordance with your engineers details. Then the membrane is dressed up around the balustrade and a protective shroud fitted to protect the joint. This is the industry standard method for fixing handrails to a flatty. You need to be quite meticulous with your setting out. The glass is only ordered once the balustrades are fitted so as to get a made to measure fit. Why would you ever need to remove a balustrade?

Page 28 of the manual, http://www.firestonebpe.com/sites/default/files/media/epdm_technical_manual_chapter_5_0.pdf

Your roofers should know this.

 

[Ydraiggoch]

Thanks for the response.

I think this is slightly different to my setup... here is a picture of my Base plate

On top of which the post will fit.

I have just had a reply back direst from Firestone, and they have offered this as a solution

This would do it, but if the minimum height of the Flashing is to be 150mm, I think its going to look a bit cr@p. Unless the Balustrade co can offer a 'Cravat' of >150mm.

As to why I would want to change it, 20 Years is a long time and my wife changes her mind like the weather!!!!

Thanks again

 

[freddiemercurystwin]

How can you get a really solid connection when fixing on top of the membrane? Worrying about the wife's whims needs to be addressed with the contempt it deserves and compromising on the detail now seems madness.

 

[Ydraiggoch]

What would be the difference in security of connection if you fix on top of the membrane or from below? The Coach bolts (120mm) will be fixing into the Trusses underneath either way?

I'm not sure the concern over changing the balustrade deserves any 'contempt'. A lot can happen in 20 years, and if for any reason (fault / damage) a base plate would need to be lifted then the Membrane would have to be broken.

 

[freddiemercurystwin]

Trusses? I thought it was a flat roof? Is it a cold roof construction then? I still don't understand the paranoia about changing the balustrades, get decent quality ones and maintain them and they'll last well.

 

[Ydraiggoch]

Maybe I'm getting mixed up with roofing terminology? This is what it is...

So Baseplates will be bolted through to the wood.

 

[freddiemercurystwin]

As mentioned is it a cold roof then? That is to say is there only going to be insulation between the joists? If so how wil the void underneath be vented?

The photo's too small but nowadays its good to build a flat roof as a 'warm roof' that is to say to have the insulation just underneath the membrane but above the structure thus minimzing any cold bridges and avoiding the need for cumbersome venting.

Hope the handrail fixing at the base is going to be an engineered or overkill solution or there'll be too much flex (ignoring the safety aspect) and the waterproof joint could fail anyway.

 

[Ydraiggoch]

My apologies, I have now found out that the product is not Firestone, it will be Fatra FF810.

I assume this makes it a Warm roof then. This looks even more complicated to install the Baseplate underneath....

The Base Fixing will be fixed as per the manufacturers instruction. They have indicated 120mm coach bolts into Timber. The main Strength / support will come from the Fixings into the brick wall of the house. As this is a U shaped Balustrade, this will be achievable.

 

[^woody^]

The basic principle is that you have a structural plate, plinth or kerb above the roof deck, and which the balustrade is fixed to and the roof cover dressed up and over. As per FMT's detail.

What will happen, is the balustrade will rock ever so slightly, potentially flexing the fixing holes. So you need the fixing point above the roof deck and into something solid.

Having the fixing down the sides of the roof reduces the risk significantly.

 

[freddiemercurystwin]

You need to know exactly how the roof is made up, never assume.