New flat roof inquiry

Customer sends me an email

Please find photos attached of our roof garden. We wish to renew the roofing material and replace the current tiles with a different option. Can you give any advice on the best way to achieve this?

There is not a great deal of depth to play with, perhaps 50mm above the current top surface of the tiles.

Damaged flat roof

Old leaking flat roof

My reply 

Yes we did a roof like this last year, here are some photos of the roof and a video showing how we did the work

Have a look at this video of what we did

Email From Customer

Dear Steven,

Thank you for the link and photos. I understand that our old tiles are asbestos, what technique do you use to remove these please?

My reply 

If they are asbestos we have a specialist remove them and dispose of them.

Email From Customer

Hi Steven,
Is that an accredited asbestos removal expert or other? If we have a sandwich affair as demonstrated with you photo sequence, how do we ascertain if there is asbestos lower down as well?
Do we need to demonstrate building regs compliance if we are stripping the roof down to the insulation level?
We liked the way that the membrane was tied into the wall surface, and the neat pebble surround. What did you do to neaten the area around the piping that had tiles cut around it?
How does the sheet membrane compare with a liquid waterproofing technique?
We live in N2 East Finchley, the roof is on top of the 3.5 storey level of the building, all access would have to be made through the building itself with no lifts available.
The type of tile solution that we are after is something alone the lines of these Indian Stones.






My reply 

Yes, the removal of the asbestos will be undertaken by an accredited asbestos removal expert.
To find out if there is asbestos lower down we would have to make some bore holes to ascertain the buildup. If the materials found looked suspicious we would send them off for analysis. But realistically I think we can take the view that the only component containing asbestos is the tiles on the surface; this is the case with 99.9% of roofs. I will be better placed to take a view on the construction of the roof after a site visit.
If the roof is being stripped back, this then triggers Part L of the Building Regulations, and then we will have to comply with them. You will have to pay a fee to the local Building Control to attend and inspect the roof whilst the insulation is being laid; this will cost you around £200.
We will also have to send them design details demonstating dew point calculations and U value; we normally deal with this end for you at no extra cost, we just pass on the costs from the council.
Where the tiles were cut around the water outlets we rearranged the pipes coming out of the wall, removed a pipe that ran across the roof under the doorstep and fitted a new gully outlet at a lower level.
How liquid roofs compare with Sheet EPDM rubber is the big question today; we like both and think both have their place in the market.
Liquid flat roof coverings are more expensive to buy and more labour-intensive to lay, so generally they are more expensive. Whereas Sheet EPDM rubber is quick to lay and cheap to buy.
I always look at the roof first and let the roof determine the covering; a complicated roof is best covered with a liquid covering as it’s easier to dress the details, a large flat roof is more easily covered with Sheet EPDM rubber. Basically the less work a roofer has to do on a roof, the less there is to go wrong in the future. This is why we dressed the roof into the walls in that way. Therefore there are no flashings, so nothing to go wrong down the line. We also opted to cover the roof with the liquid roofing material Kemper because it’s stronger, and we were going to lay the heavy tiles over the top. We could have covered the roof with EPDM, the manufacturers will allow us to use exactly the same build up, but the customer asked me for the best roof.
Think about it, both will last past the manufacturer’s guarantee. However the Liquid system is thicker and stronger and will take more punishment, so it will last longer. Again both will last past the manufacturers guarantee.
We cover the Finchley area, so this is not a problem.
Working at 3-5 storeys in height is only a problem to you, as we will have to evaluate the cost of getting all the materials up and down, to and from the roof, and this will cost you more.
There are two issues that you need to think about with this project:
  1. The amount of time the roof is going to be open to the elements before it’s watertight again.
  2. The amount of weight the stones are going to add to the roof, and can the roof take the weight?
Realistically I need to see the roof and evaluate it for you before I go any further.
Please don’t hesitate to contact me if I can be of further help.
OK  so when I get a reply I will post until then



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