Torching/back pointing roof tiles

[andywhy]

Hi

I am currently in the process of renovating my house (large 1900 semi)
The internal ceilings have been taken down in readiness of insulating and reboarding.

I have removed any loose torching from the underside of the tiles and am looking to repoint where necessary.

My question is do I need to stick to a lime based mix?? If not, what would a suitable alternative be?

Not necessary looking to restore to original spec, but I am aware of not using too strong a mix. We may have the whole roof relaid with membrane in the future and would like to clean up and reuse the tiles.

Thanks in advance

Andy

 

[Alastairreid]

01-09-2005, 08:14 PM
Touching mortar is not available ready made in dry form. It consist of sand
,lime and cow hair.

The mortar is only a pre felting method before the last war. The idea was to
stop wind driven elements from entering the loft area. Re touching is a
messy job and if done incorrect can course capillary problems. It should be
of a week mix and lightly spread on to top of tile nib and to the back of
the tile above about 25mm 1" . do not under any circumstances force the
mortar down the over laps of the tiles, as this will cause rainwater
capillary reaction. The reason for the weak mix is to make it easy to
replace damaged tiles in the future, If cement mix is to strong you want be
able to get the damaged tiles out without braking others and probably the
lath as well.

Alternative is to line the underside of the rafters with Tyvex under tiling
felt, Tyvex is light in weight, lasts longer than building paper and
breathable. Clean off all the loose mortar and start laying the Tyvex from
the top of the roof not the bottom. Use a staple gun to fix the Tyvex not
nail or you will be on the roof replacing dislodge tiles. If you decide you
want the ultimate, felt on top of tiles, its a complete re roof as felt goes
on top of the rafters under the laths. Another word of warning, don't pack
the void between the Tyvex and the back of the laths as this will lead to
condensation.

 

[andywhy]

Thanks for the info, very interesting.

Just a couple more queries

If I did choose to repoint then what weak mix should I use? Is lime essential?

I do plan to insulate between and under the rafters with celotex, taping joins before boarding over. So, is any repointing actually necessary at all?


Thanks