Renovating a 1908 stone-built house and need some help

[maznaz]

Hi there,

 

I'm renovating my second house, after a 1908 brick-build victorian house that I got some advice from here about. I recently bought a house exactly the same age in a different part of the world (West Wales) and found quite a lot of differences in construction that are giving me a bit of pause for thought.

 

The house is a semi detached, 3 storey house with room in roof construction and a blend of construction methods, namely stone exterior walls, brick bay windows, a replacement gable made from concrete blocks and an extension made also with concrete blocks.

 

I've initially removed all the interior wall coverings as they were cement with plaster over and largely all failing. Behind them I've found incredibly loose lime mortar between the stone and brick portions. In the bay windows, where the windows themselves were poorly detailed and letting in water the mortar is basically wet soil and in some extreme cases muddy. I've left it all exposed to dry out while I decide what to tackle next.

 

The first and most important thing I need help on is how to stabilise the walls so that I can do things like replace rotten lintels, put new windows in, block up fireplaces etc without risking a collapse. 

 

1. Stone walls with dry crumbly lime mortar, several voids and two first floor fireplaces that need covering up - How do I make this good to work with without bits falling out and to give a solid surface to fix in if I decide to batten? I was thinking a lime mortar using NHL3.5 but there is a lot of differing advice in period property forums ranging from pva to Limewash to lime mortar to just sand and cement.

 

2. Brick walls with wet crumbly mortar around the bay windows - I want these to be stable to receive new windows and they are currently slowly drying out. I would like to redo the looser courses of bricks with lime mortar to give a firm substrate to work with but I am concerned that I can't do so until they are fully dry which could take ages. Should I just rebuild with lime mortar before it dries?

 

Externally both of these walls are cement rendered and it might be a bridge too far to remove all that so I was hoping to make the interior breathable to compensate.

[Redbeard]

Welcome!

 

In no particular order, you say: 

58 minutes ago, maznaz said:

In the bay windows, where the windows themselves were poorly detailed and letting in water the mortar is basically wet soil and in some extreme cases muddy

 

Does this mean the windows we see in the pic are replacements? If not I would consider giving the bay plinth a long hard look. It may be the photo or my eyes, but that brickwork looks like it has 'drooped' somewhat. Yes, one can argue that in doing so it has 'found its position' but given that it appears there is a lot of raking out and re-pointing to do I sort of wonder how much harder it would be to rebuild off a new footing. Of course I don't know what is on the outside, which may also have a bearing on your decision. Again, all this assumes that the windows are not new, and will be replaced. Ignore me if that is not the case - there are other ways of skinning this cat.

 

Re lime mortar I might be looking more at lime putty rather than NHL but I am not a lime expert, just someone who sometimes uses

it.. I have no idea where he is in relation to you but you might try Nathan Goss, who teaches at the Centre for Alternative Technology near Machynlleth.

 

58 minutes ago, maznaz said:

How do I make this good to work with without bits falling out and to give a solid surface to fix in if I decide to batten?

 

For external walls can I fly the flag for a lime parge coat (air-tightness layer) even if you do decide to batten.  If you have not stopped all the air movement then 'hollow' finishes may simply become something for cold air to move behind.

 

I am jumping forward to something you have not even mentioned yet but can I assume that you intend to insulate the external walls, either externally or internally. External is arguably much better (and 'safer' from a moisture point of view) but now, when you have the plaster off, is the time to make the call on whether you insulate internally or externally.

 

Good luck with the 'project'. Loads to have fun with!

Edited December 15 by Redbeard

[maznaz]

19 hours ago, Redbeard said:

Welcome!

 

In no particular order, you say: 

 

Does this mean the windows we see in the pic are replacements? If not I would consider giving the bay plinth a long hard look. It may be the photo or my eyes, but that brickwork looks like it has 'drooped' somewhat. Yes, one can argue that in doing so it has 'found its position' but given that it appears there is a lot of raking out and re-pointing to do I sort of wonder how much harder it would be to rebuild off a new footing. Of course I don't know what is on the outside, which may also have a bearing on your decision. Again, all this assumes that the windows are not new, and will be replaced. Ignore me if that is not the case - there are other ways of skinning this cat.

 

Correct - those are the old windows which I'll be replacing. The bay is a first floor, sitting on a slightly rotten wooden lintel which explains the sagging. I'll be replacing that, probably with a concrete one prior to doing this bit of the masonry renovation.

 

 

19 hours ago, Redbeard said:

 

Re lime mortar I might be looking more at lime putty rather than NHL but I am not a lime expert, just someone who sometimes uses

it.. I have no idea where he is in relation to you but you might try Nathan Goss, who teaches at the Centre for Alternative Technology near Machynlleth.

 

Noted, thank you.

 

19 hours ago, Redbeard said:

 

 

For external walls can I fly the flag for a lime parge coat (air-tightness layer) even if you do decide to batten.  If you have not stopped all the air movement then 'hollow' finishes may simply become something for cold air to move behind.

 

I am jumping forward to something you have not even mentioned yet but can I assume that you intend to insulate the external walls, either externally or internally. External is arguably much better (and 'safer' from a moisture point of view) but now, when you have the plaster off, is the time to make the call on whether you insulate internally or externally.

19 hours ago, Redbeard said:

Good luck with the 'project'. Loads to have fun with!

 

The house is in a conservation area which makes it very tricky to get EWI into the equation. Any insulation will need to be internal which is what I'm considering.  Thanks!

 

[Redbeard]

Others will come along with different views and 'recipes' but I am a great believer in rigid (and in fewer cases flexible) wood-fibre as a solution (as both IWI and EWI)for older buildings. Many more details on request!

[Iceverge]

Have a look at @Annkers thread about IWI running at the moment.