How do I know where original level of house is/footings start?

[Lithgae]

The internal ground floor of my circa 1820 property is very close to external ground level at front of the house, and there are done dampness problems. I suspect the floor at the front of the house has been lowered in the Victorian era when the bay section was added to give higher ceilings, but wasn't to check the outer ground level had not been raised also. The front of the house is ashlar sandstone, will it be as double as finding where sandstone stops and rubble stone begins?

 

[malcolm]

Outside ground levels tended to rise over time - I think they had trouble getting horses to pull rubble skips up the hill so just distributed the rubble around the house.

I doubt you will identify the original ground level by the facing. The facing would probably be the same either side of ground level to avoid awkward transitions. If you dig down a little and have suitable facing for about 6 inches below ground level you could establish a new ground level there. I think mine ended up between 4 inches and 6 inches below internal floor.

 

[Lithgae]

Thanks Malcolm.

I dug down in a few places earlier this afternoon, and the facing is different just below the current ground level. Its a rougher more irregular sandstone below ground level, the ashlar blocks seem to stop just below the current ground level so I presume that the current ground level is only about an inch higher than it should be. The vents are nearly at ground level so I think I will just take it down a couple of inches with a slight slope away from the house then re-lay the gravel.

My suspicion is that it is the Victorians that have created the dampness problem by lowering the internal floors at the front of the house, for the sake of fashion at the time! The vents have been angled downwards through the wall and the joists are below external ground level and from what I can see through the vent they appear to be resting on the solum. The back of the house is a solid floor so there can be no through ventilation. Not sure whether the solid floor at the back is original or not.

Interestingly when I dug down at the bay section (which was presumably added in the late 1800's when the floors were lowered) you can see the layer of slate damp proof course, which isn't present on the other side at the front. I am sure I read before that this was about the time when slate damp proof courses started to appear. Kind of funny to think that they added a damp proof course to the bay window wall when none of the rest of the house has it, although I suppose they would just have been following building practice of the time.

 

[MatthewC]

...Interestingly when I dug down at the bay section (which was presumably added in the late 1800's when the floors were lowered) you can see the layer of slate damp proof course, which isn't present on the other side at the front...

One would assume that the slate damp proof course was originally above the ground level? Not doing much good if it's lower!

My house has good limestone blocks on the front (could be called ashlar, I suppose) and random rubble along the side and back. I dug in a couple of places and found that the house went further down thatn I expected, so had no qualms about (a) inside, doing a limecrete floor (425mm), (b) outside, removing over 100 tons of soil etc to lower the ground levels and (c) digging a small trench between the house and path, filled with gravel which is lower than the new ground level.

The house is beautifully warm and dry and has not had a problem in this regard in the seven years since.

Matthew

 

[Lithgae]

One would assume that the slate damp proof course was originally above the ground level? Not doing much good if it's lower!

I was thinking about this myself, but I am sure that in a previous house the damp proof course was just below ground, and I suspect this is by design so it is not visible. I think if it is just below ground level it would still be effective as it would only be drawing water from the outer part of the stone that is in contact with the ground, and the first inch or so of the ground would be relatively dry, especially in this case when its mostly gravel thats covering it. In any case the section with the slate course is the 'new' bit from Victorian times, and I'm not aware of any dampness there.

Interesting to hear your experience with limecrete, that's also something I am considering for the longer term. Not sure though, because the complication for me is that the back of the house is already a solid floor, and at a higher level than the front of the house, and the worst of the dampness appears to be where the these two levels meet. I am thinking that if I can sort out the ventilation it might help with drying out this junction. I've never quite been able to figure out if the solid floor at the back of the house is a period feature, or if it was filled in modern times. I haven't been able to find any evidence of closed off vents at the back so one theory is that the original house, which is 1820 or older, had a solid floor, and when the Victorians put in the bay section they also lowered the floor and made it a raised timber floor.

Kenny

 

[MatthewC]

It sounds as though your solid floor at the back of the house has moisture underneath it, so where the front and (higher) back meet, the dampness can show itself. Presumably the ground level at the back is higher than the front floor level? If so, a French drain there might help that dampness issue (if you have somewhere for it to drain to).

I would think it is most unlikely that the solid back floor could be original from 1820...

 

[Lithgae]

It sounds as though your solid floor at the back of the house has moisture underneath it, so where the front and (higher) back meet, the dampness can show itself.

Yes, that's my theory too. Given where it is I don't think a french drain would help, but ventilating the lower room in front might dry out the base and possibly also making that internal wall breathable. I think my first step will be to lift the floor in the front room to get in and see whats going on underneath where the dampness is, but thats a huge amount of disruption in a room I use a lot so it will have to wait until sometime when I can spend the time on it!

I would think it is most unlikely that the solid back floor could be original from 1820...

I don't know, I'm sure I read somewhere that it wasn't until around the 1800's that suspended timber floors started to become common, and before that most ground floors were solid. I also read before that even after that kitchens were often solid stone because of the need to constantly scrub floors etc, and the hallway is solid and this appears to be original and the period tiles are still under the modern wood floor that has been overlaid. I suspect that this room was a kitchen, before the modern extension. Having said that, the solid floor in the room seems to be one piece rather than flagstones etc, as if it has been poured. Maybe I should try and get an analysis of the material to find out if it is cement based or something else.