Roof Making





Introduction: Roof Making

First project, quite a low tech one... but hey...

Not that long ago, I purchased a building whose roof was made of cement sheets known to contain asbestos. As I intended to move in with my wife and kids, there was no way I was keeping it like that: So I decided to change the roof for a standard tiled roof.

An experienced mate of mine help me a lot and I thought I would pass on the info as it is really quite basic and really good fun.

Step 1: Calculation and Planning

First step is to get your figures right and order the materials. In our case, the roof is a very simple shape with just 2 planes. Each side will be about 4 meters in the slope and about 6 meters in length.

To decide on what section of wood you should use, you need to do some basic calculation:
You need to know:
How heavy are the tiles per square meter: Mine are 20 tiles/m2 and each weighs about 2.5 kilos so roughly 50 k/m2 (you can find this info in the tile manufacturer documentation(pdf))
How much snow/wind can you get in the winter: This depends on your altitude and location. I've got some tables that says for me, I need to add 70kg/m2, this is quite a lot but I live at 500m above see level and in a montaneous region.

With this, you should be able to calculate the weight per m2 that the roof will have to carry. I was quite conservative and went for twice the weight: It was my first roof and I'm putting my kids under it remember !!

You pay wood by the cubic meter, so, especially if you're doing a large roof, you don't necessarily want to oversize everything.
If you want to fine tune the cost, you can take into account the slope of the roof which alters the figures a bit, probably worth bothering if your roof is large and quite sloppy.

This photo is a before photo (it was shot in june, the finished one in february, hence the gloomy look... don't say it was better then please)

Step 2: Demolition and Preparation

Once we had all the material, we started taking down the old roof. I wore a face mask to do so and made sure I wasn't breaking any of the sheet of cements to avoid releasing asbestos fibres in the process.

Asbestos is safe to touch, it's only if it reaches your lungs that there is an issue. This form of of asbestos isn't very friable so the risk is low. My local recycling center isn't equipped to manage those kind of waste, so I had to make special arrangements: These things obviously have to be managed carefully.

Each sheet weighs about 50 kilos and is covered in moss which makes it very slippery.

These need to be disposed of properly, as I found out not every ordinary tip will accept to take care of this waste which is consedered toxic. For my part, I had to call ahead and book a slot for delivery as the guys had to wear masks and wrap all the rubbish immediately. It's not that toxic, but you can never be too carfull.

Step 3: Demolition and Preparation 2

Once the sheets are of, the wooden structure has to be ripped of: Some of the beams are damaged and the intended tiled roof will be a lot heavier: We need to have something stronger.

Step 4: The Wooden Structure

We'll only keep the largest horizontal beams, they're the only one that are sound enough and big enough to cope with the weight of the new tiles.

We start putting the vertical beams, The size you need to put depends on the weight you expect it to carry and the distance between the resting points. It's quite a simple calculation really. Don't forget to take into account the exceptional charges: Snow, wind... The slopier the roof, the less weight it caries (weight projection)

I put these beam 60cm apart as this is standard in the industry (in europe) and things come in multiple of this size for all the supplies (insulation, plasterboard...)

Make sure your beams are absolutely dead level otherwise, with time, it might not cary the weight properly and might start bending. To make sure we got it right, we draw each beam position using a clayed thread.

Don't bother putting the first and last one now as you will probably need to move them anyway to adjust to the tiling.

Step 5: Nail Job...

I put a 160 mil nail at every crossing.

Only messed up about five. Knots inthe wood can be really reallly hard.

Note how the beam are shapped at the top, I put the first beam, cut it with the circular saw and then used a template to report the correct angle on the remaining beams on the floor (better than balancing on top of the roof with electric and sharp equipement)... There is a nail on each side as well. Some people shape the beams so they rest on a larger surface. I didn't bother.

Step 6: Test Run

In order to check our calculation, we did a simultation at the bottom of the roof. Better find out now if soemthing is wrong... THis helped work out how much of the excess lenght was to be cut of the beams..

Step 7: Same a the Top...

Just did the same kind of operation at the top.

Step 8: Cutting the Wall...

Turns out the roof is resting a bit lower that the pevious one. We have to trin the wall. Big tools come in, a bit perillious, very dusty... Cut in location and then with hammer, get the bits off until you're satisfied that the wall won't get in your way.

Step 9: More Nailing...

We now need to put the underlay...

It's basically a sheet of cotton like material, that will cut winds and water from the inside. It come in 150cm width so we'll need several layer on each side be carefull to put it starting from the bottom, so that water running on top of it will end up outside and not on your bed !!

I cut the underly to the right size on the floor and set it up on the roof. It wasnt too windy so I was able to keep it in place with staples.

Step 10: Even More Nailing...

To hold the underlay in place and to make sure the tile aren't touching it (for best efficiency, there needs to be a air gap between the tiles and the underlay, roughly 50 mils.), We add some flattish pieces of wood on each vertical beam. They're nailed at the top and bottom, and will be nailed definitely at the next stage.

Step 11: Still Nailing.

now we need to add the final piece of wood, the one that will support the tiles. Manufacturer's documentation specifies what size and spacing you should use... I suggest you stick to it obviously !!

The length of these pieces of wood comes in 4 meters, have the seems to be on the top of on one of the large beams. It a good idea to draw the position of each piece of wood with a chalked thread. don't bother cutting the beam at the right length, make just sure they overhang form the roof.

Step 12: And Again

There again, don't bother putting the first and last one as they will need to be fitted to the tiles.

Step 13: Tiling...

Last step...There, you need some help. You need to be at least 2 on the roof and one on the floor.

The best way is to actually throw the tiles... I know it sounds stupid, but it works out really well. We only broke four or five out of a thousand. Have a guy on the floor to open the packs and throw them one by one (he he) to a guy on the lower part of the roof. That guy then throws them to the guy on the higher part of the roof who lays them.

It's good to have the same guy to lay the tiles all the way as you can spot the difference between one layer and another. It's good as well to progress in the same fashion all the way, otherwise you can spot the difference again.

As you reach the edges, you can fit the missing bits of wood at exactlty the right position. You can also cut the excess overhanging wood.

You need to use half tiles on the edges, but it's quite straight forward.

I didn't bother nailing any of the tiles apart from the one on the edges as they're the ones holding all the others.

Step 14: The Top

Cut the large beams so you've got a flat level surface at the top.

Nail another beam there and then put the round tile there. Nail them properly as they're holding all the other tiles.

Step 15: That's a Job Well Done

Get yourself a well deserved beer.

overall, it took 2 week ends to do, with 2 people most of the time. I'd never done anything that serious DIY wise before and really enjoyed everything of it... I've done everything in that little place and could document it for you if you want.

I've been living this house for about 9 months now. And really enjoyed doing it over. It makes it really special to sleep under a roof that you've made with your own hands.

I've now started doing up a much bigger place... I get a real kick out of this...



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    what material did you use for the roof and we're can I find it

    1 reply

    Amazingly, the link in the description still works, almost 10 years on:

    see here:

    Sourcing these will probably depend on where you're based, I was in France at the time, went to my building supply merchant (PointP for me at the time), chose something that I liked that they were stocking and looked it up on the net for the datasheet (Or whatever you call the equivalent for tiles).

    I had to order the ridges specifically as they didn't have the ones I wanted in store, but that was fairly straight forward (even though I messed the count, or they messed up, can't remember, but you can see one missing in one of the photos)

    quality read! cheers

    The top of the rafters should be on the sides of the ridge, and the where are the birds mouth cuts on the rafters at the top of the wall.

    Good Job. I should note that the asbestos in the roof would not cause a problem, unless you yanked it out. The asbestos is impregnated in the substrate and is just about impossible to get out, unless you find a way to make it into a powder (like sawing it.) I went to York Uni and a better part of the damned place used asbestos reinforced concrete. It wasn't a health hazard, but it weirded some people out. Besides structural support, the great thing about the asbestos cement roofs is that they will not burn, nor will they decay over the decades. And as we well know, the wet British Isles weather will eat about anything over time. In the future, there are products that seal the roof from underneath and increase it's RF factor in one go! But still, well done. The roof came out looking quite nice and professional.

    Just interested. What was the cost savings benefit of purchasing the existing foundation and remains of the structure versus erecting one from scratch on empty land? I imagine it was significant or you wouldn't have done it. The reason I am asking is the structure didn't look very secure in the first picture with the leaning wall. Personally I would not have had the courage to try and restore it for use as a home instead of for a workshop or a studio. I am guessing empty land is very costly/rare where you were, yet cheaper with an existing dilapidated structure upon it? Excellent results though. Good job.

    6 replies

    Well, not everything is just about cost really... I just love old stones and character properties... Of course if you're looking for the cheapest deal, you can go live in a caravan in a dodgy car park... But it's not quite the same as being in a place with a history and an atmosphere... The structure was sound, it's been there for centuries. The previous owner did the first part of the job (in discutable fashion, with concrete slabs and asbestos roof sheets... The main drawback with the place was that it was a bit damp...

    Just wondering what you did with the Asbestos sheets. Its really great stuff. Personally, I would have kept it. You would have had no Asbestos exposure with that particular product. Cement Asbestos board, or "CAB" has all the asbestos contained within the cement. it has good insulation qualities, and it is classified as "Non-Fryable: meaning, the asbesos content cannot become airborne. Which is the only hazard with Asbestos. That CAB roof would have been in good condition a 100 years from now if left alone. The one definite drawback of CAB is it is truly ugly. But from an engineering viewpoint, its about as perfect as a product can get. I have worked with the US state department and the US dept of defence on Asbestos jobs around the world. I worked on the Oregon capitol building removing the asbestos there and there was a lot of it but, I do know something about this subject though. It looks like a great property and I hope you have lots of fun with the renovations! JL

    Yep, I agree with you. The main reason for making the change was indeed aesthetics. A few of the sheets were damaaged as well and you can't buy replacement anymore.

    I agree, I wouldn't want to live in a caravan park. Living in the french alps must have been beautiful. Were there any other structures on or near the property? The reason I ask is that I am wondering what the was benefit of an old bread oven over an old house, for example, that needed fixing up. The dampness might put me off. I imagine you were able to sell it for quite a bit more than what you bought it for? It's good for a single artist or a weekend vacation cottage. Maybe you could rent it out. Are there any pictures of the job from the inside?

    Sorry, my daughter (16month payed with my keyboard while I was replying !) ;)

    It was lovely. This building was one of two. There was a thatched roof farmhouse but it collapsed during the 50s after the owners failed to maintain it during the war. The other building, which was still in a reasonable state was a barn... The plan was to move into the former bread oven, and do the 3500 sq foot barn conversion in the evenings and week ends... Unfortunately of fortunately, we had two kids in the meantime which was delightful but complicated a bit our situation. Moral support did vanish and I had to resort to giving it up. even though it was heartbreaking, I think I didn't really have the choice as that project was way to big for me to do beside my day job. I didn't loose money on the property but didn't max out either... I think the fact that I sold it as a building site prevented me from making heaps of maney. I'd say I covered all my material cost but not the hours I spent on it. Had I finished it, it would have been a totally different matter a very profitable. But at the end of the day, I really enjoyed the experience and learnt a lot which is worth a lot in itself ! By the way, the dampness did go away with a bit of heating I do have some pictures of the inside and of my other project, they're just not online at the moment.

    Just wanted to pop in a quick suggestion. Anyone who is putting a roof on like this ought to invest in "Hurricane Brackets". These are basically little strips of metal meant to better hold the roof on in high winds. Example here (Number HC1). These hold on a bit tighter than just nails, and are required by the 2006 Uniform Construction Code. Wasn't sure if you used these, maffiou, but thought I'd make the suggestion to anyone doing the same.

    2 replies

    Hello Erik, I didn't use these brackets. Now, you have to bear in mind that this property is in French Alps, not in the US, and we don't have hurricanes here as far as I know. There are other local constraints though like the underlay and other local specifics like snow, wind, etc... I don't have the pretention to say my work on this roof was of professionnal standard. I tried not to cut corners, and do the best I could...

    Oh, absolutely, and it looks like great work. I just wanted to mention that for anyone else that was building a roof.

    Wow.. all that hard works makes me want to hire someone :D My husband and I are looking to purchase a large/old bed and breakfast to remodel and make our perm. home. It needs a new roof.. and I seriously doubt we have what it takes to consider it a DIY project. Are you putting up clay tiles or something like terra cotta? Pretty Cool! Good work!

    1 reply

    I've sold this place now... Didn't get to finish it, sadly... Moved from France to the UK...

    Steps 13-15 could be elaborated A LOT MORE.....what kind of tiles are they? Show pictures of them going up one at a time.... next roof: more pictures. Love the bldg love the roof :)

    1 reply

    I wanted to do a lapse time video of them going up, but it failed miserably !! I probably have more photos somewhere but I need to digg them out !

    I'd be interested in seeing a close-up of how the facade tiles were hung/attached... that has me a little confused. Nicely done space, but did you really move in that small space with your wife AND kids? It looks like a beautiful office/workshop/garage, but there doesn't seem enough room to fit a kitchen, bathroom, living/dining, AND multiple bedrooms. mabey i'm just missing something. I could see a single man living there quite contently, while fixing the place up, and even a couple,. But with children, it just seems too small. of course, that's probably part of why you're working on a "much bigger place" my metric conversion calculator is rusty, butthose tiles must be THICK to require such large, closely spaced rafters. Hard to tell from the pictures, but those look like 80mm square timbers. I built a simmilar roof, though using terra cotta tiles, that required only 40 by 60 mm boards(2X6dimentional lumber is close to 40X60 I think) I envy your morning cup of coffee on those roof weekends. the view looks spectacular! when you get time, let's see some more of those photos. but don't rush. We understand, with this project, you were litterly trying to keep a roof over your head!