GRP cladding

[chrisb]

I've got planning permission for a large side and rear extension to my house (semi-detached) with a condition that the materials used in the construction of the external surfaces should be of similar appearance to the existing brickwork. I believe this to be Marston brick - see photo below. These are apparently no longer available and Selco's brick matching service have come up with an alternative - that doesn't match very well (see image with matched sample), they are also relatively expensive at 61p each exVAT.

 

From the outset I was keen to avoid a brick outer skin to my timber frame as it takes up valuable space and adds little to the thermal properties, but struggled to find any alternatives. I've now found a firm doing GRP brick-effect cladding in panels which are probably just as good a match as the matched sample above, but slightly different. This would be good as I could gain another 3 inches of internal room width, be quicker to put up and I hope cheaper overall.

 

Does anyone have any experience of this type of cladding? I can only find the one firm doing it so far, which is a little worrying. I also need to research fire resistance (it is offered as standard, or class 1 flame protection) and check it would be acceptable to the planners in order to discharge the condition.

 

Any thoughts much appreciated!

 

Chris

[PeterW]

That looks like a London - have you not got any you can pull out as a sample as matching by photo is a nightmare. 

 

Have you considered a brick slip system ..?  

[SteamyTea]

In the early 1980's we made some stone look alike pillars for the Heathrow Excelsior Hotel.  I think they are still there.

We also made a few GRP chimney surrounds for air condition units.  They looked like brick.

They can be made out of Class1 material no problem.

As for longevity, if you remember the old building by the Elephant and Castle roundabout, the red cladding was GRP, was over 40 years old when they pulled it down.

It had faded a bit, but then it was red in colour, which is a tricky pigment at the best of times.

 

I am surprised that GRP is not used more in the UK.  I is used a lot in the Middle East.

[Ferdinand]

Yep- that one looks like London Stocks.

 

On GRP, well made it should last 40-50 years, and to make it well is simple. Our family biz used to do this occasionally as a special.

 

In this application, the obvious problem I can see is that those segments are so small that you may end up with an obvious tessellating pattern. If they are that small they really need 5-10 slightly different 'tiles'.

 

The only way to be sure is to look at one they have already built and be sure that you are happy. 

 

Fire wise, GRP is OK until it goes, then it GOES. But it will take something very very hot to set it alight and take some time. We used to make spiral staircases from it, and they were allowed to be sold.

 

Ferdinand

 

[chrisb]

Gents, thank you very much for your speedy replies. I can remove a couple of bricks above the garage door if I arrange some weather protection. I guess then I should take a tip round the BMs to seek out  a match, or is there a smarter way?

 

I have considered brick slips, but certainly for the matched brick its very expensive as each brick needs to be cut. I have some stock slip samples which are a lot more economical. I haven't really identified a system to mount the slips on - there seems to be a few options, some of which alter the construction of the wall with insulation, cavity etc. Guidance and opinions very much appreciated please.

 

@SteamyTea & @Ferdinand, I'm reassured by your posts - I was beginning to think that with only one supplier that I found, I was onto a crazy idea, but it seems more like its one of those things that just never caught on here. Any suggestions for suppliers welcome.

 

Thanks

Chris

[Ferdinand]

To reemphasize.

 

The look is critical - it could be made to look like a fake rock in a fishtank or the fake stone edges to one of those grp ponds.

 

So very important to go and look at a real example.

 

I might even argue for cladding your garage first to sanity-check it.

 

I guess one downside is that when people tap it it may sound "plastic".

 

Ferdinand

[SteamyTea]

17 minutes ago, Ferdinand said:

Our family biz used to do this occasionally as a special

What was your family business, our paths may have crossed in the past.

 

9 minutes ago, chrisb said:

Any suggestions for suppliers welcome.

Not really as I have been out of the business for a while.

You could look for local GRP companies and see if they know, or suppliers.  Not the sort of business happens in town centres these days (hard to believe that we had 400 litres of acetone a few feet from the Chilterns Railway line you could smell the factory in Wycombe high street).

[Ferdinand]

Do some Googling for brick Grp cladding.

 

There are a number out there.

Edited January 26, 2017 by Ferdinand

[chrisb]

I've taken this a bit further today, including a discussion with the BCO. The stumbling block at the moment is prevention of the spread of fire, apparently not the same as flame resistance. The manufacturer (http://www.grpbuildingproducts.co.uk/) can make it flame retardant, but not fire resistant due to the pigment in the gelcoat. Both he and I are now looking into intumescent paint to see if that would be an option to make it meet the BC regs.

 

@Ferdinand I've just searched for the terms you stated and found a few more suppliers to call tomorrow. Interestingly they don't appear with my previous searches of "brick effect cladding". Thanks.

[SteamyTea]

15 hours ago, chrisb said:

The stumbling block at the moment is prevention of the spread of fire,

Not sure what the BCO is really after, but there are Class 1 gelcoats, Crystic Fireguard 72PA is one.

[Ferdinand]

Huh? If it is in use elsewhere such reports should be available off the shelf, surely?

 

Does he mean spread of fire on the outside?

 

How is this different to eg wood or plastic siding cladding?

 

F

Edited January 27, 2017 by Ferdinand

[chrisb]

Another call to the BCO - who is very helpful.

 

The relevant requirement is 60 minutes fire resistance as I am building to boundary. There is also a spread of flame standard, which he will look up, but the suggestion was that a product that is compliant from a fire resistance perspective will also likely comply with spread of flame requirements.

 

@SteamyTea Thanks! I mentioned this to the chap at GRP Building Products and he said the issue was that the pigment used in the gelcoat adversely affected the fire resistance properties. Of course, I have no idea if it's just his gelcoat and pigment, or a more general issue?

[chrisb]

OK, some progress. I was barking up the wrong tree (slightly). The BCO's requirement is that the whole wall has 60 mins fire resistance from either direction, not the cladding per-se. I have discussed this with the TF supplier and they have done this before by swapping out the OSB on the outside and replacing with fermacell.

 

The cladding can then be applied directly to the fermacell if it is waterproof (as with GRP) and no breather membrane is required.

 

Naturally, the TF supplier says that it should be the architect that comes up with the design and the architect says it should be the TF supplier as it's an integral part of their wall! I need to speak to the fermacell tech dept and the TF supplier again to work out who is going to do what. The compounding factor is the inside layer - the architect is suggesting fireline plasterboard as an alternative to another layer of fermacell as it will be cheaper.

 

Any thoughts on wall construction?

[Ian]

9 minutes ago, chrisb said:

The compounding factor is the inside layer - the architect is suggesting fireline plasterboard as an alternative to another layer of fermacell as it will be cheaper.

Any thoughts on wall construction?

 

For the internal skin - you will get 30 minutes fire protection from a single layer of plasterboard or 1 hour by using 2 layers. The main alternative is a single layer of 15mm thick Gyproc Fireline board.

 

Ian

[ProDave]

My garage has to be lined with two layers of 15mm fireline, with staggered joints. I don't know how long fire protection that is supposed to give?

 

If you want a "non brick" finish, how about a render finish, if it's totally different it solves the brick matching problem.
 

[chrisb]

19 minutes ago, Ian said:

 

For the internal skin - you will get 30 minutes fire protection from a single layer of plasterboard or 1 hour by using 2 layers. The main alternative is a single layer of 15mm thick Gyproc Fireline board.

 

Ian

Is there a marked benefit of one technique over the other? I kind of like the idea of double thickness for more secure fixings if I want to hang things on the wall, but I wonder if the Fireline will be easier to install and therefore cheaper?

 

12 minutes ago, ProDave said:

My garage has to be lined with two layers of 15mm fireline, with staggered joints. I don't know how long fire protection that is supposed to give?

 

If you want a "non brick" finish, how about a render finish, if it's totally different it solves the brick matching problem.
 

 

I'd far prefer a rendered finish, but planning dictates it must look 'similar' to the rest of the house unfortunately. I have established that there is no way to actually enforce that as there is no requirement to submit materials for approval prior to building and there is no completion inspection, but I don't think I'd get away with a totally different finish.

[PeterW]

2 hours ago, chrisb said:

I kind of like the idea of double thickness for more secure fixings if I want to hang things on the wall, but I wonder if the Fireline will be easier to install and therefore cheaper?

 

Fireline once skimmed is nearly as expensive as fermacell - and one 15mm panel gives you the 60 minute fire protection you need and you can hang cabinets off it. You cannot do that with plasterboard ...

 

fermacell is also an easy DIY job too. 

[Ian]

On 2/22/2017 at 18:00, chrisb said:

Is there a marked benefit of one technique over the other? I kind of like the idea of double thickness for more secure fixings if I want to hang things on the wall, but I wonder if the Fireline will be easier to install and therefore cheaper?

 

I don't think there's any marked benefit of one system over the other - obviously you would be handling half the quantity of boards using the Fireline. It would come down to which option was cheapest I guess?

 

15mm Fermacell may be your best bet as PeterW suggested due to its strength but I have no idea how the price compares with normal plasterboard.

 

Ian

[Mr Punter]

Fermacell can go soft and and mouldy if it gets wet.  You would need their or others cement based boards if you are using it as a direct cladding or render backer board.  Fermacell is gypsum based and has BBA as external sheathing, but it cannot be exposed to the weather.

 

Why not just have OSB sheathing, breather paper, vertiical battens to create 25mm cavity, then render carrier board or brick slips?  I also like some of the fibre cement plank cladding systems like Hardie.