It’s not often we get asked to look at a flat roof as large as this and unfortunately our free estimate wont cover the cost of surveying this roof and reporting back the findings.
This flat roof is a round 1500m2 and is covered with an old type flat roofing membrane with welded joints, this type of roof is still being fitted but we consider it to be one of the older generation flat roofing materials.
I’ve taken a walk around the inside of he building and seen where the water is penetrating, externally I have examined the roof and can see lots of design faults, I will be submitting a preliminary report suggesting that thermal imaging of the roof is undertaken to show where the insulation is saturated this will help identify the areas of the roof where the roof has taken on water, then we can scrutinise each joint and visually inspect the membrane for holes punchers or rips.
At this stage I think we will be cutting out all the wet insulation then repairing the roof using a liquid roofing systems such as GacoRoof.
Information from customer regarding his leaking flat felt roof.
Hi,
We have a leak on a felt flat roof extension in London NW6 4SS, which is about 10 square meter. We are looking to replace with EPDM. Could you please come around for a quote?
Reply By email from London Flat Roofing.
EPDM over felt is not recommended as its black and attracts the heat in the summer melting the felt and making the rooms under the roof uncomfortable. To stop this happening the roof will need a OSB Board overlay before the EPDM then flashing’s so I would suggest a price of £1400.00 +flashing’s and scaffolding if needed.
An alternative roof is the 3M Scotchkote Urethane Roof Coating SD650 the finish is light gray so reflects the heat, although much more expensive that EPDM rubber, easier to lay and now over boarding needed so would suggest a cost of around £1000.00+vat + any flashing’s and scaffolding needed
Both prices will be subject to how clean the old roof is and its accessibility.
All +vat
Guarantees up to 25 Years are available
Have you got access to the roof, if so can you send me some photos? if So can you send me a photo from outside the property
If you also send me the address I can look this up on Google earth.
Realistically old mineral felt roofs have to be a thing of the past now.
There are lots of new flat roofing materials on the market, such as EPDM and the new 3M SD650, same day roof system.
You can see on this photo that the owner of the property has been trying to fix this old flat roof by applying some sort of liquid sealer to the joints of the felt.
New flat roofing materials dont have joints, EPDM comes in large sheets and the new liquid applied flat roofing materials don’t have any joints at all.
Making the flashings out of the new flat roof materials is also easy. Unlike the old flat roofing materials, the new materials are alway flexible and the flashings can easily be formed from the same materials and fixed to any wall.
Detailing round pipes and skylights is also very easy especially using the new liquid flat roof systems
If you need more information about flat roofing please don’t hesitate to contact me at London Flat Roofing.
I want to address the first part of your question as posted bellow
Where new insulation is placed on top of the exiting roof structure, if the existing wall is not built up to the underside of the roof (as a minimum standard) then heat from the room below can bypass the new roof insulation and cause a thermal bridge. If this is how the work is done then surface condensation is very likely to occur on the inside of the ceiling/wall junction leading to potential mould growth. It is essential that the eaves is sealed to at least the same standard (in terms of U-value) as the external wall to prevent the thermal bridging/condensation from occurring. In practical terms, because the roof height is being raised, a new fascia will need to be provided, and this will allow access for the wall to be built up without the need to resort to an internal intervention.
First of retrofit building regulation and new build regulation are different Par L and Part L1b
The problem you have observed is mainly in the retrofit situation as in the new build this is easily address, however its very often over looked by the builder the roofer the district surveyor everybody.
One of the problems we as so called good builders and good roofers face is when to speak up and when to keep quiet over the things we observe on building sites, personally I can only think of one building site I have been on that all building work was undertaken correctly and this was because the builder was the owner and he had the time and the money to deal with all details and to be quite frank the reason I specialise in roofing is so I can be at the top of the pile be paid for what I do and do it properly or don’t do it at all, its a nice situation to be in and its taken me some time to achieve.
Personally I point out the problem to the customer and tell them that the detail at gutter and softie level needs to be dealt with explain the consequences if they don’t want to address it its down to them. I think you have to also look at this from the customers point of view. The customer is only replacing the roof because he has to not because he wants to he has an expense he can do without roofing is expensive then its explained to him that by replacing the roof he has triggered part L1b of the building regulation and the roof need to be insulated and this will cost £x more so he asks you to draw up a specification you bring in the the gutter softie details together with the insulation and the price is expanding all the time, he asks why you are so expensive you explain you are doing the work correctly show him drawings and details and he just cannot stretch that far, also you know the DS (distic surveyor) and all other bodies are not dealing with this space so the customer has the option to leave it for the time being and pick it up the next time he carryou out renvation to the house ( we all know this will be never)
So lets look at the mistermeaner and what could hapen and what from experiance douse happen.
Normally the roofs we tern around to be warm roofs are not build as cold roofs infract when they were build I dont think the terms warm roof or cold roof existed, lets go back to the 1900’s if you built an extetion in london you had a lath and plaster on Joists with close barding over and the roof covering on top the roof didnet have any ventilation built into it as it didnt need it no substantual heat in the rooms below now insualtion in the caverty no insuation over the roof no inperviouse membrains anyware holes allover the place between the close boards at the gutter board no particler close care to details. I must also state that lath and plaster ceiling with distemer over would alow lots of movemnet of vaper throuth. its only when you start painting them with new emultions that have PVA adheasives built into them that you stop lots of the moister from transfering through.
So as the years go on all sorts of changes take place heating doubel glazing insualtion stufed all over the place without thinking of sweating vapour barriers or ventilation, relisticly I dont know of that meany vergin flat roofs most of the roofs we work on have got some osrt of insulation between the joists and realistically the consichsis of this are rearly taken into acount whne doing due point calulation and working out just what the consiquesive of placing insualtion over the roof stucher could be.
I think you have hit the button right on the head
Yes we pick this up all the time with thermal imaging
Yes this eaves junction on tiles roof and on flat roofs is the hardest part to insulate correctly this also makes it a verry expensive operation to insult correctly.
I’m living in Ireland and saw one of your videos – yeah, you tube works!
I have a few flat roofs and I’m a fairly handy diy’er. Do you think it’s feasible for me to do the liquid plastic job myself?
It’s particularly appealing as it doesn’t require the labour intensive aspect of stripping off the old roofing material.
Presently, insurers here won’t cover houses with flat roofs, or else they quote exorbitant premiums – maybe this liquid
plastic roofing (with the appropriate certification) would resolve that problem.
Ive blogged on DIY Liquid EPDM before, today I and 24 hits asking about liquid EPDM in the UK
From my understanding there is only one supplier of liquid EPDM in the UK. I will get the link for you and post it.
I have experimented with it and its not easy to use. I certainly don’t think its a DIY job and I also think that there are problems with distribution it to the non-trade because of how volatile it is.
Just keep this thought in mind, a liquid roofing product such as liquid EPDM should always have some king of depth control system, if you take Kemperol v210, Triflex Liquid plastic or GRP they all have some kind of reinforcement that also acts a depth control without such a materials the only controle to the depth of material being laid is by weight per meter, and the problem with that system is you can place more materials on one end of the roof and less on the other!
but not sure if it is the same as what you are using there. Also seems a bit expensive. The one you are using is a nice consistency good flexible finish.
Any help would be much appreciated there is not much information on liquid rubber coatings.
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.
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:
The amount of time the roof is going to be open to the elements before it’s watertight again.
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.
In this new video I show some problems that I see more and more, the lead is oxidising because of lack of ventilation.
Todays building methods and materials mean that if you don’t ventilate your roof correctly the roofing membrane will stop all movement of air and water vapor this can then lead to sweating when the conditions are correct.
The new EPDM rubbers and some of the liquid rubbers are vapour permeable however this does not mean you don’t have to vent the roof it just means that a small amount of water vapor can move through the membrane
New page added to the site today all about how much a new roof costs I also have a roof cost estimator being launched next month this will help people find out just how much the different roof materials cost.
I’m asked all the time how much a new roof cost and realistically nobody puts their prices up on the net I don’t understand this!
Anyhow I’m going to change this the new roof price estimator will work out the price of a new roof based on criteria entered by the user, it will collect the information then send the user a PDF with prices and options of several different new roof materials.
I
EPDM Rubber and liquid Flat Roofs 