Advice on sub floor inspection and blocked airbricks please

[alan9310]

Hello,
I need some help with how to solve this problem and would love to hear other people's advice!

The situation
I bought my house six months ago and on the survey, it said that the sub floor ventilation has been compromised, and this will result in the gradual deterioration to timbers due to condensation dampness because the extension at the back of the house is full width and the rear 2 air vents have been covered up. The survey recommended getting a 'full sub floor inspection'. I decided to go ahead with the purchase as I didn't notice any damp, the place smelled dry and seemed well looked after. I had planned to get the sub floor inspection carried out in a year or so's time.

However this week I’ve noticed that a meter or two of the skirting board has very slightly come away from the wall and the paint has cracked slightly at the join (see pic). When I press the skirting board back towards the wall, the slight crack closes under pressure and moves away again when released. I painted the walls in August and so I know this is something that’s happened recently.

There is an ever-so slight smell of damp by this part of the skirting board. There is a slight raise and dip in the floor by the skirting board area, and also in the same position in the front room (marked on floor plan). They're not springy or spongy, but it is noticeable that the level is different and they make a noise when you walk over them.

Please see the floor plan below, but it’s a small Victorian mid terrace C1860–1900, two up two down, with a full width single story extension at the rear C.1970. An injection damp proof course was helpfully(!) installed in the 1990s all the way around the property. There are plans of this in the house documents and you can see the injection holes outside at the front. The house is very cosy and dry throughout and rated C (probably due to all 4 fireplaces being blocked up – planning to open these up somehow to improve airflow in a few years).

I take good care to dry washing outside, ventilate and heat effectively (to 19º) to avoid mould. I have hygrometers to monitor humidty and keep it between 40% and 60%.

Proposed solution
When buying the house, I found this solution (https://www.periodproperty.co.uk/forum/threads/insufficient-airbricks-at-rear-options.14747/) to what seems a very similar problem, which I think could solve it.

Please see a floorplan attached with the location of the current air bricks, the skirting board area, and my proposed solution for venting bearing in mind it's a mid-terrace house.

Questions
This is my first buidling project as a new homeowner and so I would be so grateful if I could have some advice as to whether the following solution is correct?

1. Get a subfloor inspection
2. Replace the joists if rotting
3. Install ventilation vent in fireplace hearth to connect with sub floor (as suggested in above link), and any other possible location for another vent subject to builder's recommendation. At the moment this firepace wall is blocked up/covered over.

I do not want to do this work myself and would love to know what type of company I need to look for to do the following three things: sub-floor inspection, replace joists etc, install vents. Presumably the inspection shouldn’t be done by a company who can also do the work due to risk of upselling unnecessary/incorrect solutions! If anyone has any recomendations of good companies in the South that would be great too.

From my research, I want to avoid anything involving injection damp proof coursing or adding concrete, as I understand that old houses need to breathe.

Thank you so much!

 

[Cubist]

I see what I think is a laminate floor in the room photographed, if this continues throughout you may face problems getting a sub-floor inspection that does not damage this and perhaps over a larger than expected area. Get the intended contractor to look at this and tell you what can be reasonably expected. Additional vents to compensate for those lost would be helpful in any event.

Is it safe to assume that the walls in which you have found dips solid brick?

All houses move as it undergoes repeated heating and cooling cycles over time. The various materials will expand and contract and often to different extents and any wooden components will be most affected by such. Cracks at the juncture of wooden skirtings and plaster walls are typical and often any caulk previously used to close such gaps will fail at some point to open a crevice or crack. Those shown in the photo appear to in the paint join between the skirting and the wall and such are almost totally unavoidable. Sand back the paint from, re-fresh the caulking and re-paint as needed.

 

[alan9310]

I see what I think is a laminate floor in the room photographed, if this continues throughout you may face problems getting a sub-floor inspection that does not damage this and perhaps over a larger than expected area. Get the intended contractor to look at this and tell you what can be reasonably expected. Additional vents to compensate for those lost would be helpful in any event.

Is it safe to assume that the walls in which you have found dips solid brick?

All houses move as it undergoes repeated heating and cooling cycles over time. The various materials will expand and contract and often to different extents and any wooden components will be most affected by such. Cracks at the juncture of wooden skirtings and plaster walls are typical and often any caulk previously used to close such gaps will fail at some point to open a crevice or crack. Those shown in the photo appear to in the paint join between the skirting and the wall and such are almost totally unavoidable. Sand back the paint from, re-fresh the caulking and re-paint as needed.

Thank you for the tip!

Yes sadly it's laminate throughout the bottom floor of the original house which I'd like to replace with real wood when I have the funds.

The dips are in the floor, but yes the wall to the right is solid brick as far as I can tell. Yes the floor dip area definitely feels different from in the summer, perhaps its picking up extra moisture from elsewhere too.

 

[Cubist]

Dips in wooden floors and near walls are typically a result of decay to the ends of the underlying joists which may be/have rested against the brickwork. Damp rising from through the masonry can transfer to the timber to induce rot which can then spread into the floorboards. The laminate flooring will dull any sense of movement of the underlying plank boards and the associated joists but are you seeing or feeling any vertical movement when weight is applied and removed from the areas of concern.

Another thought worth investigating occurred when I looked at the floorpan you supplied earlier. This suggests that you're seeing dips near the door openings - have you confirmed that the doors are hanging properly and that the top hinge has not been sprained/bent by a small amount? This can cause the door to bind in some places during its travel from open to closed while moving freely over other sections of its arc.

 

[alan9310]

Dips in wooden floors and near walls are typically a result of decay to the ends of the underlying joists which may be/have rested against the brickwork. Damp rising from through the masonry can transfer to the timber to induce rot which can then spread into the floorboards. The laminate flooring will dull any sense of movement of the underlying plank boards and the associated joists but are you seeing or feeling any vertical movement when weight is applied and removed from the areas of concern.

Another thought worth investigating occurred when I looked at the floorpan you supplied earlier. This suggests that you're seeing dips near the door openings - have you confirmed that the doors are hanging properly and that the top hinge has not been sprained/bent by a small amount? This can cause the door to bind in some places during its travel from open to closed while moving freely over other sections of its arc.

Thank you for your reply, that’s helpful to know. Yes in the dip areas there is slight vertical movement of less than a half centimetre I’d say when standing on it, but it’s still noticeable. The door hinges seem to be fine and nothing wrong with the door frames either.

Do you have any advice on the type of builder I need to contract who would understand how to solve the issue with respect to old buildings and not to resort to concrete? I’m based in the south so any company recommendations would be great! Thank you

 

[Cubist]

Any good general builder should have the skills needed - the trouble with that though is finding one. Get your underfloor inspect by someone you can trust first though and do not trust the opinion of a general builder you find until he confirms what you have already been told.

 

[alan9310]

Any good general builder should have the skills needed - the trouble with that though is finding one. Get your underfloor inspect by someone you can trust first though and do not trust the opinion of a general builder you find until he confirms what you have already been told.

Oh that’s a great tip, thank you so much!

Hoping to report back here later on the project’s progress to help others with the same issue.

 

[alexander]

sorry to be the bearer of bad news but if there is no ventilation under the sub floor you could have major issues with the floor boards under the laminate, you first thing to do is lift some of the laminate to access the floor boards then you will need to lift some of the floor boarding to see what is happening below, just done one this week & there floor is rotted completely through only having one air brick vent for the whole of the floor area then having water pipes under it creating the ideal condition for condensation mould and varies beetles to thrive.
good luck