Which retro-fit/refurbishment dry ridge system

[wobbly2]

Does anyone know of a retro-fit/refurbishment dry ridge system suitable for concrete tile on a garage roof. I’ve seen that Manthorpe do something but it is for use with their plastic ridge tiles not concrete.

Also can someone suggest why the underfelt on this garage roof is dressed so that it laps over the ridge from one side (a) and continues down the second side (b) but the continuation starts at the ridge sitting on top of that from the first side as per the diagram below (I hope that makes sense)?

 

[mfarrow]

Marley do a system but TBH I think bedded ridges look better.

You decided that 2mm gaps between tiles is far too much to bear considering pointing?

And the reason the underlay looks like that is the roofer fouled up.

 

[wobbly2]

Marley do a system but TBH I think bedded ridges look better.

You decided that 2mm gaps between tiles is far too much to bear considering pointing?

And the reason the underlay looks like that is the roofer fouled up.

I think the Marley system requires the top tile batten to be removed, which is not good because the verges have only just been rebedded, however, I'll take another look on their website. I agree bedded ridges look much better, especially on single storey buildings. The dry ridge solution was suggested by Sandtoft technical as a means of overcoming the likelihood that, due to excessive rafter spacings (e.g. 920mm & 1000mm being the worst), the roof may/will flex enough to break the mortar bond created whilst moving along the ridge to lay subsequent tiles. In addition, Sandtoft suggested that because their system incorporates a membrane, which fits between the underside of the ridge tiles and the top of the main tiles, no water should be able to get onto the "fouled up" underlay at the ridge. The tiles battens are 25 x 38 except for the top ones which are 25mm x 38mm doubled up with 19mm x 38mm.

To be honest I wouldn't know if a 2mm gap between ridge tiles is too small to be mortar bedded, I was told it was; the person who told me this suggested I use silicon sealant to fill/seal the gap.

 

[mfarrow]

As I've said before you will get a gap between ridge tiles anyway. No ridge tile is formed perfectly, the tiles in the top row aren't completely flat, and the are then it doesnt matter because no ridge beam is completely flat.

The guy who said 2mm is excessive must be pulling your leg.

Can you reinforce the roof from undernear with something which braces the rafters to spread the load whilst working? Kind of like a purlin? Bit of 6×2 perhaps?

 

[wobbly2]

Can you reinforce the roof from undernear with something which braces the rafters to spread the load whilst working? Kind of like a purlin? Bit of 6×2 perhaps?

Wot a brill idea - why didn't I think of that, moan moan mutter mutter.

Thinking about it though, it's as much the battens deflecting that'll cause the flexing issue.

 

[mfarrow]

Again, you can reinforce the battons from underneath. You'll be able to feel for them under the underlay then just screw another batton length to them.

 

[wobbly2]

Again, you can reinforce the battons from underneath. You'll be able to feel for them under the underlay then just screw another batton length to them.

Presumably you mean cutting and fitting lengths of batten between the rafters? Presumably I just need to reinforce the battens where the rafter spacings are excessive? How many rows of battens do you think I should reinforce, just the top row?

I'm probably worrying about nothing but I've just had a thought - My understanding of the natural sag of the underlay is that it takes any water (that gets past the tiles) towards the centre of the sag thus draining that water away from the battens and the batten fixing nail holes through the felt; wouldn't reinforcing the battens from underneath the underlay remove this sag and possibly create another issue?

How about reinforcing the battens at their lower edge above the underlay, which would not remove/reduce the sag? Measuring the rafter angle at approx 20 degrees and the top tiles row at approx 18.5 degrees there should be sufficient room to install a substantial piece(s) of timber i.e. 44 x 100 screwed to both the existing batten(s) and rafters, see sketch. I wouldn't be able to install and fix the new timber(s) the full length of the roof without breaking up the verge but I should be able to at least span and fix across the problem rafter spacings which are mostly toward the centre of the roof.