Roman Triple Roll tiles, minimum angle ?

[bernardgreen]

The roofs on my two outbuildings leak, one more than the other.

The tiles on both roofs are ( I am informed ) Roman triple roll and the overlap on one roof is about an inch and only slightly more on the other. The slope of the roof is about 45 degrees. Now that the ceiling has been removed rain water can be seen running down the underside of the tiles. Closer examination shows that the over lap is too small and water is dripping onto the next tile so close to the top that it is running over the top edge of the tile and round onto the underside of the tile.

I am told that the amount of over lap is set by the size of the mitre on the corner and that to get more over lap each tile would have to be cut.

Also several of the tiles have spalled and some others are porous.

Is the 45 ° angle too shallow for this type of tile.

This is the roof with the greater overlap which leaks far less than the other roof.

To complicate matter the buildings have Conservation restrictions on what can be done to them.

Is there a similar looking tile that can have a larger over lap ?

 

[terrypin]

45 degrees is fine, I would think.

Most tiles have a minimum 75mm headlap, saying that I have little experience in using old triple roman(roll)tiles.

There are a few tiles that have similar profiles but you may be limited in choice.
Eg. Double Roman tiles: 75mm min headlap.

 

[bernardgreen]

thanks

 

[catlad]

Can you not strip the tiles off and lay some membrane and then re-tile. I have never used a tile that you can't change the overlap.

 

[bernardgreen]

Membrane is one option and may be the one that has to be used.

 

[bernardgreen]

After a bit of thought and some driven rain getting under the tiles I haved decided to re-use the tiles on new battens and with a membrane rather than felt.

Next question is which membrane to use.

 

[terrypin]

You will still have to alter the headlap, water ingress will still occur if you don't.

 

[bernardgreen]

With the tiles on the roof increasing the overlap ( head lap ) is not possible and changing the tiles to another more suitable type would involve a long drawn out "discussion" with planning and conservation departments of the local council.. The building is in a Conservation Area and in the curtiledge of a Listed Building

With a membrane the ingress can be dealt with with the water being directed into the gutter.

Originally the building was used as a butcher's slaugther house where a bit of water dripping from above wasn't a problem. So the choice of tiles around 1950 was biased by what was easily to hand. Then around 2005 it was changed to be a shop and had a ceiling installed. This ceiling has been soaking up the drips from the roof and slowly deteriorating until a couple of months ago when it has to be taken down before parts of it fell down.

 

[terrypin]

But the water will then be directed onto the wooden battons, a lose lose situation.

 

[jontop]

I call these Belgian pan tiles and they are quite a challenge.
You should be able to lay these with a 2" lap (without cutting them) this 'should' keep the rain out. But ultimately these are a bad design driving rain may still get in .
When battening it is important to be accurate with the gauge
The challenge comes when laying them, because they are clay one tile will be slightly bigger (longer or wider) than the next, so you need to select a tile for a particular place and so on. Can be slow.
I would choose a new tile, a clay pan tile that looks similar . Much quicker to lay, water tight and a guarantee