Gus Potter Posted January 13 Share Posted January 13 Here is a puzzle. I'm doing an upgrade job on a listed thatched house in Scotland.. there are only about 200 of them left that are meaningfull in Scotland. To cut a long story short the thatch was relaid completely in about 1950 - 1953 by a new town development corporation.. think Milton Keynes. In their wisdom they thought it would be a good idea to guard against fire. To that end they overlaid the rafters with asbestos cement sheets and thatched on top of that. Now I truck up and want to knock a lot of the ground floor walls out to make it open plan. But to do that I need to support some big point loads from chimneys etc. That means I need to tie the structure back into the top part of the roof. But the Client wants to add insulation on the first floor above the ceiling chords, near the shoulders of the chimney breast you can see below. I'm thinking.. hey Gus leave that alone as I could make things even worse! If I insulate the ceiling in the upper floor I'll shift the dew point in even further and could end up with a compost heap on the roof. Any thoughts folks? I'm appealing as there may be BH folk that can give a bit of advice.. am I being too cautious? The climate up near Glasgow is not condusive for thatch in general. I can't show you the front of the building as it would make it identifiable, the front looks great, Crittal windows etc. The chimney is one of the point loads and there is not a lot to stop it falling into the garden. My steel design and temporary propping involves pre bending (pre loading) the steels to make sure nothing moves.. post for another day on how you do that with off the shelf DIY stuff. Mind you if I get this wrong you'll read about it in the papers as it's right in the town centre. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 14 Share Posted January 14 Can't really help, but have you considered adding extra insulation to other places. Doing that may get the thermal losses down to a reasonable amount and leave the thatching unaffected. Alternatively, improve the airtightness and run a large MVHR unit to get the moisture out, then you should be able to add insulation anywhere without worrying too much about where water will condense. I thought it was usual for thatched places to have roof fires when new owners took over. 1 Link to comment Share on other sites More sharing options...
Kelvin Posted January 14 Share Posted January 14 70 years is a long time for a thatched roof to last. Has it been well maintained? I know their lifespan can be extended by replacing the top layer. 1 Link to comment Share on other sites More sharing options...
ETC Posted January 14 Share Posted January 14 Bulldozer! 1 Link to comment Share on other sites More sharing options...
Russell griffiths Posted January 14 Share Posted January 14 7 hours ago, ETC said: Bulldozer! I must admit I agree. You’re just braver than me to say it. 1 Link to comment Share on other sites More sharing options...
Adrian Walker Posted January 14 Share Posted January 14 7 hours ago, ETC said: Bulldozer! It’s a listed building, so that might be very difficult or expensive. 1 Link to comment Share on other sites More sharing options...
ETC Posted January 14 Share Posted January 14 It’s listed but you’re knocking internal walls down and there’s a shed load of asbestos. Sorry can’t square that circle from a historic building viewpoint. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted January 14 Share Posted January 14 @Gus Potter Is this your on place, or a clients? Link to comment Share on other sites More sharing options...
saveasteading Posted January 14 Share Posted January 14 3 minutes ago, SteamyTea said: Your on place, or a clients 21 hours ago, Gus Potter said: Client wants to add insulation Removing internal walls in a listed building needs permission too. 2 Link to comment Share on other sites More sharing options...
Gus Potter Posted January 15 Author Share Posted January 15 Hi all and thanks for the input, much appreciated. On 14/01/2024 at 06:26, SteamyTea said: Alternatively, improve the airtightness and run a large MVHR unit to get the moisture out, then you should be able to add insulation anywhere without worrying too much about where water will condense. Nice idea, will consider. On 14/01/2024 at 08:36, Kelvin said: 70 years is a long time for a thatched roof to last. Has it been well maintained? I know their lifespan can be extended by replacing the top layer. Yes it's been looked after, was completely redone I think circa mid sixties and maybe again after that.. but no one seems to know for sure. On 14/01/2024 at 08:57, ETC said: Bulldozer! Not an option in this case, need to work with what is there. On 14/01/2024 at 15:58, Russell griffiths said: You’re just braver than me to say it. The truth will set you free! ..but thanks for being sensitive. On 14/01/2024 at 16:08, Adrian Walker said: It’s a listed building, so that might be very difficult or expensive. As above. On 14/01/2024 at 16:23, ETC said: It’s listed but you’re knocking internal walls down and there’s a shed load of asbestos. Sorry can’t square that circle from a historic building viewpoint. There is a suggestion that it may be a gypsom based product thus asbestos is not a problem. Futher investigation is in hand... hopefully it will be a false alarm. 23 hours ago, SteamyTea said: Is this your on place, or a clients? Client's 23 hours ago, saveasteading said: Removing internal walls in a listed building needs permission too. Indead, listed building consent application in hand, there is no charge in Scotland.. one of the few things that are free these days. Will report later as project progresses. Thanks again all. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 15 Share Posted January 15 26 minutes ago, Gus Potter said: Client's You can have some fun with this without being reckless with the customer's money. If that ceiling/rafter covering can come down easily, you may be able to hide some MVHR pipework up there and possibly a bit of extra insulation, though that would probably need to be hung below the rafters, so depends on headroom. I think this one, if your client agrees, is one for a blog, with lots of pictures/videos. Link to comment Share on other sites More sharing options...
George Posted February 1 Share Posted February 1 Additional ventilation through the gable walls should alleviate issue with moisture build up in the thatch/roof space. You lose the insulation from the thatch but you could more than make up for it in the ceiling. Agree a MVHR system would give additional assurance (and maybe clear out any residual asbestos fibre that have floated down). 1 Link to comment Share on other sites More sharing options...
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