How essential is this roof repair?

[ruthie2012]

Hello. This is my first post and also my first really old cottage. Please forgive me if my terminology is not quite right.
We have just bought a cottage that is believed to date from the 1700's. The roof dips (dishes?) at one end as shown (the area to the right of the chimney):

The surveyor said that this is due to the weight of the slate being too great, over the years, for the timber construction of the roof (he said the rafters have not been properly linked) which is shown here:

The above photo is taken pointing upwards to the affected roof area showing how the rafters are offset.

The surveyor advised us to get this sorted out, along with repairs to the chimney and said we should allow £10000.

Of course there are builders willing to do the work, but before we go ahead we would like to know how we should approach this work and what it is essential to do. We are particularly concerned to not end up with a new-looking roof.

Does the dishing mean that the roof is definitely unsafe? Do the roof slates have to be stripped back? Do the existing rafters have to be removed or can they be strengthened somehow from the inside without changing the shape of the roof?

How do we find out for definite whether or not the roof is likely to cave in? i.e. does this work really need doing at all?

I'm sorry if this sounds a bit naive but we want to retain the authenticity and character of the cottage and not change things we don't have to (or spend money we don’t have to).
If there's not enough information here please let me know what else is needed.

Thank you
Ruth

 

[88v8]

Hello and welcome.
Not naive at all. Too many people are rushed into unnecessary work, especially on roofs.
It doesn't matter that the rafters aren't opposed. That wouldn't have prevented them from sagging. They've sagged because they were too flimsy when they were installed. Nor does it necessarily matter that they have deflected over the years, they're still there..... The rafters in our roof - also C17 - are a lot wonkier than yours.

Do they have worm?
Are they rotten?
Are there knots in the bottom chord near the centre?
If not, leave well alone.

The roof has obviously been off already in the not-long-ago, as it's felted - it wouldn't have been like that when the slates were new. The roofers who felted it presumably didn't think it needed mending...
As you say, it's part of the character. Too easy to make everything straight and flat and square, and then wonder where your lovely old house has gone....

At the most, I might prop the rafters off the joists. Post a pic of the joists below the rafters, let's see if there's a propping point. A few bits of 4" x 2", that would cost, errrm, £30...

Or, you could nail Anbrac strapping along the lower chord of each rafter to increase their strength. Another £30... Can't find the stuff I want... it's about 1" wide, on a roll, perforated... hmmm.

£10,000 ? They're avin a larf

Ivor

 

[vicky whitworth]

Hello Ruthie and welcome. It looks like you have a lovely cottage just from the roof line and chimney. I'm no technical expert but I have learnt that stuff doesn't fall down all the often despite the woes that surveyors and builders bring suggesting it might. When did you last read of a house falling down or the roof crashing in. (Guys, don't take that as an excuse to post all sorts of scare stories). There must be a way to prop it up at a tiny cost.
What's the problem they suggest with the chimney? It looks great to me. I like wonky! My surveyor told us that our hayloft floor would fall down at any moment as the joists were rotten. Ok we did deal with it eventually but after four years of walking to and fro on it nothing happened - and my other half is 16 stone (I know, he needs to lose some weight. It's not his fault he needs a beer in the evening!)
Vicky

 

[Pford75]

Echo the comments on how lovely the roof looks wonky.

It's difficult to see from your photos, but it does looms if some of your roof is not properly joined to the ridge? I would suggest that it would be a good idea to introduce some additional bracing, but this could be done with the roof in situ and shouldn't be too expensive.

 

[LadyArowana]

Is the cottage listed? ( welcome to the forum BTW )? Either way it might be worth consulting with your local Conservation Officer, if they are too busy to visit you "on site" then taking the pix you have posted here to them might be a good first step. I know some councils offer a drop in day when you can just turn up and consult a CO.

 

[skier-hughes]

Q1. Does it leak?
Yes - you need to do some work on it.
No - it's doing it's job properly.

We have several roofs, one of which is wonky under rosemary tiles, but this wonkyness comes from the age of the wood, no doubt after a few hundred years it's got a bit tired in places.

Can't tell from those pictures, but is the wood old, some looks quite new. You could add some extra supporting timbers alongside those already in, but it'll be a game and a half to get them as wonky to fit the current roofline

Can't think of a Q2!!

 

[middi]

If there is no evidence of rot in the roof rafters, and as other have suggested, all you need to do is strengthen these rafters from within the roof void and save yourself a bundle of cash. Rafters of that age ( probably oak or elm), will show some signs of wood worm mostly confined to the outer sapwood, this is no cause for alarm and neither is the " sagging" action that is typicallly associated with that age and method of construction.
The best way to achieve the extra strength that may be needed ( for peace of mind) is to brace the existing rafter with collars ( 4 or 6 x2 treated timber screwd onto the sides of opposed rafter pairs. You may need to fix a short " nogging" between adjacent rafter to acieve a better fix for collars.

What I would be very carefull about, is to try and support the " sagging" roof weight above any ceiling joists. These joists may not be up yo the job and all you end up with ( eventually) is also a sagged ceiling.
The stabilising repair, as I have suggested, will stop the roof elevation caving inwards and the roof weight will be transfered to the rafter feet over the vertical wall plate. ( make sure these lower section of rafter feet do not show signs of rot)

I have a feeling that " your" surveyor is covering his backside by immagining a new roof with brand new roof rafters. NOR REQUIRED, judging by your pictures, and do not be afraid to get a second opinion from someone that repairs these buildings

Middi

 

[AMc]

A surveyor is unlikely to be sued for advising you get something fixed that doesn't need it - they can be for suggesting something doesn't need fixing that subsequently does.

I'm not being disparaging about the profession but it is not in their interests to be casual about risks, they are advising you and your lender of the potential problems you may find and the upper end of the costs of fixing them. The £10K estimate would pay for a lot of roof work. If you bought a house with a dilapidated roof and hadn't budgeted for it then it would be on his/her head.

If this is in the written report than I would try and speak to the surveyor on the phone or better in person to discuss the report - very few people do this but it makes sense to ask follow up questions My surveyor was a lot more forthcoming person to person than he was in the report because as he clearly told me - he was professionally liable for the contents of the report - on the phone he told me a lot of the things in the report were based on the worst case. He was also much more helpful after the mortgage was approved and we'd exchanged as his advice went from warning us about a potential purchase to helping prioritise what we needed to do first.

As others have pointed out - the felt shows that the roof is reasonably new. If it's not leaking then the chances are it will be OK at least for now.
If the roof needs reinforcing then you can either do it yourself (as above) or find a reputable local joiner who can come and reinforce it from within. This shouldn't be expensive and isn't urgent either.

Good luck and try not to panic!

 

[ruthie2012]

Thank you very much for all the replies. Really helpful. We're going to get up in the roof space next week and take a good look and get the extra photos asked for above - and I'll be back.

Either way it might be worth consulting with your local Conservation Officer, if they are too busy to visit you "on site" then taking the pix you have posted here to them might be a good first step. I know some councils offer a drop in day when you can just turn up and consult a CO.

The adjoining property (the one to the left of the chimney) is listed, but ours is not, apparently due to 20th century modifications. We are in a conservation area though so this might be a good idea.

The roof has obviously been off already in the not-long-ago, as it's felted

We believe the last time it was off was in the 80's.

What's the problem they suggest with the chimney?

The surveyor said that repairs are required to the plinth of the stack. He couldn't see what the full extent of the work may be, but said the inward facing side had suffered from deterioration. Also water ingress is likely to be evident around the back of the stack. We don't know if water's getting in or not yet but we will try and find out.

Here's a better picture:

Anyway, we will get up there and get a really good look and some more pictures and then I'll come back and answer the other questions. Thanks again.