Felt Flat Roof - Several questions

DespotDespondency

Hi,

I've just moved into a new house with a bituminous felt flat roof. There are a couple of points that came up in the survey with regard to the roof and some clarification would be appreciated.

1) The survey states that there are no granite chippings on the roof. Probably a naive question, but what would be the purpose of putting chippings on the roof? Is it just a matter of purchasing a bag of chippings from a builders merchant and laying them on the roof? How much chippings would suffice for a 3x2.2 metre flat roof?

2) A second point raised in the survey is that `Current building regulations require flat roofs to be ventilated and this has NOT apparently been provided at the time of construction as ventilation grills do not exist. It is important that adequate ventilation is provided at the earliest possible time to minimise the possibility above the ceilings in the flat roofed areas.' What sort of ventilation should I be looking at here, e.g. an extractor fan in the room below the ceiling? It is a bathroom and there is no extractor fan, so I'm thinking of installing one anyway.

Thanks in advance.

[Deleted User]

DespotDespondency wrote: »

Hi,
Probably a naive question, but what would be the purpose of putting chippings on the roof? Is it just a matter of purchasing a bag of chippings from a builders merchant and laying them on the roof? How much chippings would suffice for a 3x2.2 metre flat roof?

"Specialised flat roof aggregates can help to protect flat roofing membranes from ultra-violet rays of the sun which cause deterioration and provide a protective layer for light traffic. Aggregates can also be used to weigh down the insulation on inverted roof designs. By laying fair coloured aggregates on the membrane, heat absorption is controlled. They can also provide a decorative area bringing the flat roof area into a usable environment for inhabitants to relax and enjoy."

Source: http://www.brettpaving.co.uk/specialised_aggregates/products_applications/dried_aggregates/roof_chippings

So are you going to be walking on this flat roof?

I've personally never heard of putting chippings on a flat roof before...but I'm not an expert.

Anyway, sounds like it could be something you can do yourself.

kwmlondon

From memory I think you need to use an adhesive, traditionally it was bitumen, and then shove the chippings on top so that they stay there.

The vent issue is not so much about venting the room below as the roof - there's a gap between the ceiling and the top of the roof and this space could start to get condensation. I think it's just a matter of installing a couple of vents which is a quick job for a carpenter, but worth going onto a local trade website and finding out quotes.

ian103

this can sometimes be used instead of solar chippings

http://www.toolstation.com/shop/p99690?utm_source=feed&utm_medium=googleshopping&utm_campaign=googleshopping&mkwid=SFyNdI9f&pcrid=25046346503&gclid=CNqf4IqkxbgCFUbHtAod6DcAFQ

cyclonebri1

The chipping are used to prevent the dark felt or bitumen from over heating and melting/ageing , just apply a bitumen adhesive around the perimeters and cover the roof.

Grills or vents are normally positioned under the eaves in the soffit plates, plenty available, just drill or slot out and snap in the insect proof item.;)

ca55ie

Also try to avoid walking on the roof once the chippings are down as the sharp points can cause tiny holes in the roofing material.

kwmlondon

Just out of interest and on the subject of flat roofs - if I had a single-storey extension built and wanted to turn the top into a terrace, how much more expense would that be to have a paved flat roof than, say, just a normal sloped roof?

Just wondered if anyone had done anything like this and could let me know if it's hideously expensive and not worthwhile, or reasonable?

cyclonebri1

kwmlondon wrote: »

Just out of interest and on the subject of flat roofs - if I had a single-storey extension built and wanted to turn the top into a terrace, how much more expense would that be to have a paved flat roof than, say, just a normal sloped roof?

Just wondered if anyone had done anything like this and could let me know if it's hideously expensive and not worthwhile, or reasonable?

I don't quite get where you are at with this but, if you ever build a single storey extension with the remotest possibility of extended further upwards, detail this at BC stage and have them treat the foundations of the build as 2 story with terraced roof from the onset


A bit of advice for the op, if unlike the guy above that I was answering, you have no intension to continue upwards, you should consider if it is possible to ad a conventional tiled roof over the existing extension

kwmlondon

cyclonebri1 wrote: »

I don't quite get where you are at with this but, if you ever build a single storey extension with the remotest possibility of extended further upwards, detail this at BC stage and have them treat the foundations of the build as 2 story with terraced roof from the onset

I'll give a bit more detail. I'm buying a house with a conservatory out the back. It's okay, but my plan is to replace it with a single-storey room that I can turn into the kitchen/dining room. If I took it up a storey then I'd just be extending a bedroom and it doesn't seem worth the hassle. However, if I put a flat roof on the extension I could have a terrace above the kitchen. Screens on either side would mean that there would be no issue with privacy over the neighbours. I just wonder if would be a good way of using the space - I'd like a terrace up there.

I know I'd need planning as the conversion from a bedroom window to a french door would make it obvious that the space was being used differently.

Is this a reasonable thing to do?