Solid Concrete Floor

[Bart1664]

Been told I had posted this in the wrong section so trying here:

 

We have recently purchased a stone cottage that was built in 1969 on the foot print of a much older cottage (probably dating back 200 years). However, we don't have any detail of the quality of that build and I have three questions we hope someone can offer advice on. The external foundations show a red brick (engineered bricks?) base followed by a visible dpc and air bricks around the property. It is faced in traditional stone as apposed to brick and does appear to be constructed with a cavity wall.

 

We are now unexpectedly experiencing some patches of damp on the internal walls (see pics) mainly in the lounge just along the top of the skirting boards. We have done a great deal of research on damp and we are not swayed by the usual arguments of 'rising damp' and the usual remedies suggested by many of the 'experts'!

 

We have stable moisture readings in the lounge of 49% and 52% and regularly vent the rooms.

 

We have had the room examined by a builder who is also a 'qualified' damp assessor (whatever that is) and he suggests that the plaster used in a recent attempt at renovation by the previous occupants was the 'wrong sort' and was probably in contact with the solid concrete floor. He used a gadget that had about 5 settings on it to probe the floor and walls and said that he was getting high moisture readings at the damp patches and that below one point on the concrete floor showed that the be 'saturated'. 

 

His suggested remedy is the take off all the internal plaster and re apply using the correct one (maybe with lime in it) and ensure that there was a sufficient air gap between the floor and plaster.

 

This then brings me on to my second issue - The concrete floor

 

The builder has suggested that 'potentially' this may not have a membrane within it and he suggests once the plaster is off the walls he will grind back the surface and lay a membrane across the whole floor and under the internal walls.

 

Does all this sound correct/reasonable?

 

My final question is that I have had conflicting advice regarding the external pointing of the stone work. Lime mortar or concrete? I'm told that because the cottage has a cavity it does not need to be lime mortar and can be normal mortar.

 

Hoping for some guidance.

 

Many thanks in advance.

[Mr Punter]

This could be condensation.  Was there any furniture in front of this?  Has the house had cavity wall insulation?

 

Are the external levels at least 150mm lower than your floor and the DPC?

[markc]

That screams wet cavity insulation to me, is this on all walls or just outer?

[tonyshouse]

Looks like a water leak to me, gutter, overflow pipe- heating or water.

 

the crystals will ne sodium nitrate (dissolve in water) 

 

could be wet getting into the wall, what is on the other side of the wall. 

[Bart1664]

Tony/Mark/Mr Punter

Thank you for your replies on the damp.

 

The outside gutters and down pipes are all quite new (put in by previous owners)

The outside concrete path that goes all around the house is almost level with dpc although there was a 6" void against the house itself the previous owners had simply filled this with decorative stones that also then came almost to the level of the dpc. I have since removed all the stones and looking to have the concrete path removed and lowered along with the rainwater drains.

 

There isn't any cavity insulation as far as I can tell 

 

The damage is does seem to be restricted to outside walls but mainly in the lounge where its visible. 

 

The outside mortar does require re-doing in places and particularly at ground level hence my question regarding lime or normal mortar to be used.

 

[tonyshouse]

What is in/behind/above that different coloured wall at the far end of the bottom pic? 

[Bart1664]

1 hour ago, tonyshouse said:

What is in/behind/above that different coloured wall at the far end of the bottom pic? 

Hi Tony

It's an external chimney stack. However the majority of the internal plaster damage is at the internal corner of the two external pictures ?

 

 

 

[tonyshouse]

Sorry, clutching at straws,  unusual to get damage on internal skin, Where is the nearest radiator?  

[Bart1664]

37 minutes ago, tonyshouse said:

Sorry, clutching at straws,  unusual to get damage on internal skin, Where is the nearest radiator?  

No. I'm happy to accept any straws....clutched or otherwise!

 

If we call the pic with the black down pipe PIC1 and the other PIC2.

 

PIC1 - nearest rad is along that wall (away from down pipe) but about 7-8 feet away

PIC2 - no rad along that wall only log burner recessed. Although I'm fairly certain that the large external chimney appearance is almost 'folly' like as it seem far too large for what is on the other side and there is very minor damage anywhere near the burner (almost so you can't see see it)

 

I think what we plan on doing before any internal destruction is:

 

1. Remove and lower the external concrete path all the way round

2. Repoint all brick and stone work

 

So two questions here is:

 

1. Lime or normal mortar - given it has a cavity I'm told I don't need to use lime

2. Should I seal up foundation bricks (below DPC) after they have been repointed with some type of proprietary paint sealer?

 

Edited November 28, 2020 by Bart1664

[tonyshouse]

Normal cement mortar is fine but I wouldn’t bother and it certainly is not the problem 

 

I also would not remove the concrete path for this reason, again it isn’t the problem. 
 

what is upstairs? Is there a window above or near that corner?

[Bart1664]

Thank Tony

 

I really appreciate your thoughts.

 

The ground level (pic2) shows the foundation bricks, dpc and air brick. The first layer of mortar does appear very crumbly and I believe it to be lime but the rest of the house appears cement so at least that first layer of mortar will require renewing. We had quite a bit of rain yesterday and you can see the dampness laying on and in that course which can't be right?

 

The top floor windows mirror the ground floor (see pic) and were installed a few years ago (again by the previous occupants) and the rain water drains are on and in places (we have 5) actually above the dpc so I'm told these really need to be below dpc and if so I'll have no choice but to lower the path.