Repair vs Re-tiling Roof

[activelab]

Hi everyone,
After the heavy rain we had a few months back my roof started leaking, enough that it appeared to be coming through to the bedroom below. There's a couple of cracked tiles that look like the obvious culprit and I can see where a couple of others have been patched up before with some form of silicone (moved into the house a year ago).
The problem I have is that I believe the roof has been insulated with polyurethane foam, as far as I'm aware there is no felt underlay, as a result all the tiles are fixed in place, I've no doubt attempting to remove them will result in several tiles breaking meaning replacing just a few is out of the question.
I've had a couple of builders round to get a quote, both around 3500 (2k of which was labour) to re-tile the front side of the roof. Both builders commented the other tiles generally seem in good condition, though they weren't impressed with the insulation method (I've noticed there's generally a lot of debate about polyurethane foam!).

So onto the questions...
- Am I missing a simpler solution here to just patch up the tiles with a silicone or similar product? Neither builder suggested this, though it didn't occur to me to ask at the time.
- 3500 at the moment is simply out of the question, I've done other reasonable size first-time DIY projects since moving in but I am a complete amateur at roofing - is this a job to be left to the professionals?

Your thoughts would be much appreciated!

 

[pinenot]

What age is the roof (likely the age of the house?) and what kind of tiles are they??

Suggestion - Get a quote for replacing broken tiles only as opposed to the whole roof! Also if there are the same homes/tiles adjacent how do they compare, you might want to talk to your neighbours re any known problems...pinenot

 

[activelab]

The house is Victorian, approximately built 1900, clay tiles. I had the builders round just to take a look, but they said as trying to remove tiles would be impossible without them breaking that re-tiling would be necessary, which is why I was quoted on full re-tiling.
I think the roof may have been re-done within the last 10 years when a loft conversion was done.

 

[pinenot]

I had a roof of clay pan tiles, treated with care they can be handled quite well without much breakages. I'm not saying your builders are telling porky pies, but given the job to price, with instructions to lay aside say 20%, they would save a heck of a lot more than that because they would be quids in. As an aside, Gumtree is awash with offers of reclaimed clay tiles, one wonders where they come from

So I would suggest you phone around some more roofers and make a point of stating that the tiles are indeed salvageable (no qualification) and get some quotes...pinenot

 

[noseall]

I had a roof of clay pan tiles, treated with care they can be handled quite well without much breakages. I'm not saying your builders are telling porky pies, but given the job to price, with instructions to lay aside say 20%, they would save a heck of a lot more than that because they would be quids in. As an aside, Gumtree is awash with offers of reclaimed clay tiles, one wonders where they come from

So I would suggest you phone around some more roofers and make a point of stating that the tiles are indeed salvageable (no qualification) and get some quotes...pinenot

Did you actually read the initial post?

The problem I have is that I believe the roof has been insulated with polyurethane foam........as a result all the tiles are fixed in place, I've no doubt attempting to remove them will result in several tiles breaking .......builders .....weren't impressed with the insulation method (I've noticed there's generally a lot of debate about polyurethane foam!).

Do you know what foam is or what it does when sprayed on stuff?

 

[activelab]

Hi Noseall, I understand it's a good insulator but different sources argue how 'breathable' it is and if leaks (like mine) can cause rot and structural problems.

I've looked at the tiles myself pinenot and they're pretty solid, googling suggests the material used is consistent with this problem... "The adhesion between foam and slate also makes later reuse of the slates impossible, adding significant extra cost to the eventual reroof. Because of these 2 problems, spray foam lining timber framed roofs is now regarded as bad practice in the UK."

 

[pinenot]

Whilst spray foam insulation/adherence is now regarded as bad practice (your words) for those who have it, yourself included, therefore I think it might just be worthwhile pursuing the alternatives.

I think most roof that were done this way used expanded polyurethane foam in some form or another and it's very easy to cut, sand, saw and dissolves (messy) with acetone...does that allow for some thinking outside the box?

In order to reduce costs, I'll presume in all instances its better to retain and repair rather than remove and re-tile! and I'll assume that access to the interior foam is reasonable. The foam itself is easily replaced via a can and some care, Oh! by the way the foam cures with the aid of moisture so be prepared to spray the areas of repair prior to application.

First off the area (if multiple) or tile should be located, as much as poss., then the foam/tile should be cut from the inside (almost like cutting a grass sod, but upside down) I've used a hacksaw blade with a masking tape handle, an old carving knife with a flexible blade or at times a hand saw (good for cutting flush with the rafter sides) once the foam is cut it's fairly easy to break off the tiles, honest, proceed in this way with all the tiles so identified (if necessary) tease some acetone into any clingy joints. Unless your building is within a mile of the sea, tiles will likely be nailed every third row (don't know about clay tiles though) assuming they are of the cleat design, which allows for easy slip up,out of the road access to freed tiles (as already described) Replacement tiles can now be inserted starting from the bottom row and those above re-positioned. Finally to preserve the integrity of the roofing matrix, expanding foam can be layered into place replacing that removed to facilitate the above procedures...pinenot

 

[noseall]

Whilst i admire your enthusiasm for thinking outside the box, the building trade, in most cases, is far too simplistic to justify such deep thought.

Sometimes you have to grit your teeth and get on with it using brawn and a good pair of gloves.

Can you imagine spraying acetone inside a loft!

Whoever sprays such destructive materials on their roof tiles deserves a good slap.

 

[Alastairreid]

@pinenot

Have you ever came across this stuff in Scotland?

Being that we have sarking boards in all the older properties.

I aint!

 

[pinenot]

Nope, but I've worked with foam alot