Possible dampness under laminate floor

TheCyclingProgrammer

I’m hoping somebody can give me some advice about a potential damp issue.

We had laminate flooring laid downstairs throughout our living and dining room (it’s all one open room) about two and a half years ago. It’s laid on top of fibre board underlay, which is on a vapour membrane on top of floorboards.

About a year ago we noticed some black mould along the bottom right of the patio doors. The laminate floor meets the patio doors here and there’s some threshold trim covering the expansion gap. We cleaned off the mould and at the same time noticed a musty damp smell coming up from the floor in this area. It’s only present in this corner of the room. You can smell it where the laminate meets the patio and around the bottom of the skirting board. The smell isn’t anywhere else, not even on the other side of the patio doors.

The mould didn’t come back but the smell lingered. Until today, when I noticed mould growing again. It was about the same time as last year. Again I cleaned it off.

I know it’s important to keep a subfloor ventilated. Before we had the laminate fitted we had extra air bricks fitted. Unfortunately we were not able to fit one in this corner as there is a conservatory which presumably covered the original air brick. There’s a note on the original conservatory paperwork from 12 years ago about relocating one airbrick but there’s no sign this was done. An air brick on the side of the conservatory dwarf wall appears to just be ventilating the cavity. So I assume this corner is a bit of a dead spot in terms of ventilation and airflow which would explain why theirs a damp musty smell there and nowhere else.

The question is, how much should I be worried about this? The guy who fitted the laminate has quoted £140 to lift enough boards (which will require removal of skirting and a radiator) so we can lift the floorboards and investigate and then relay afterwards. This seems reasonable and I’m willing to pay it if it’s worth doing.

At best I imagine it could just be damp soil below the subfloor but at worst I’m worried about dry rot setting in. I have no idea if the smell is dry rot. There are no other symptoms. No signs of dampness on the floor or walls or skirting and no spring to the floor that would indicate an issue with the joists.

If we lift the floorboards and the problem is just stale air due to lack of ventilation how can we ventilate this corner of the room when there’s no external wall in that area to vent to?

Thanks.

magn8p

The answer to your question is definitely not a simple yes or no. And the lifting the laminate to see what's going down under is perhaps the only way to find answers.

The more information about sub-floor ventilation can be found here - http://www.simplifydiy.com/walls-and-ceilings/sub-floor-ventilation

All the best.

TheCyclingProgrammer wrote: »

I’m hoping somebody can give me some advice about a potential damp issue.

We had laminate flooring laid downstairs throughout our living and dining room (it’s all one open room) about two and a half years ago. It’s laid on top of fibre board underlay, which is on a vapour membrane on top of floorboards.

About a year ago we noticed some black mould along the bottom right of the patio doors. The laminate floor meets the patio doors here and there’s some threshold trim covering the expansion gap. We cleaned off the mould and at the same time noticed a musty damp smell coming up from the floor in this area. It’s only present in this corner of the room. You can smell it where the laminate meets the patio and around the bottom of the skirting board. The smell isn’t anywhere else, not even on the other side of the patio doors.

The mould didn’t come back but the smell lingered. Until today, when I noticed mould growing again. It was about the same time as last year. Again I cleaned it off.

I know it’s important to keep a subfloor ventilated. Before we had the laminate fitted we had extra air bricks fitted. Unfortunately we were not able to fit one in this corner as there is a conservatory which presumably covered the original air brick. There’s a note on the original conservatory paperwork from 12 years ago about relocating one airbrick but there’s no sign this was done. An air brick on the side of the conservatory dwarf wall appears to just be ventilating the cavity. So I assume this corner is a bit of a dead spot in terms of ventilation and airflow which would explain why theirs a damp musty smell there and nowhere else.

The question is, how much should I be worried about this? The guy who fitted the laminate has quoted £140 to lift enough boards (which will require removal of skirting and a radiator) so we can lift the floorboards and investigate and then relay afterwards. This seems reasonable and I’m willing to pay it if it’s worth doing.

At best I imagine it could just be damp soil below the subfloor but at worst I’m worried about dry rot setting in. I have no idea if the smell is dry rot. There are no other symptoms. No signs of dampness on the floor or walls or skirting and no spring to the floor that would indicate an issue with the joists.

If we lift the floorboards and the problem is just stale air due to lack of ventilation how can we ventilate this corner of the room when there’s no external wall in that area to vent to?

Thanks.

PhilE

Im no expert in this, but there has been a corner of my Mums house which had been getting mysteriously damp, near to a subfloor vent. There was also some mold in the spare room and bedroom.

The windows in the house are exceptionally good, the solution thus far has been to vent the house more and then heat the air straight after. Since then, the problem had abated.

Always a good place to start with any mysterious mold issues.

Also, even heat distribution in your home.

missile

I would not ignore it.

We had an issue with damp under our laminate floor.

We thought it minor, but decided to lift a board or two to investigate. The damp was extensive.

magn8p

Great views from your balcony!

How did you cure it by the way?

missile wrote: »

I would not ignore it.

We had an issue with damp under our laminate floor.

We thought it minor, but decided to lift a board or two to investigate. The damp was extensive.

TheCyclingProgrammer

I’ve asked the guy the fit the laminate to book us in for January to lift the floor in that corner so we can investigate. Even if it’s just stagnant soil in the subfloor it’s worth the peace of mind.

TheCyclingProgrammer

Missile - what was the cause of your damp? A leak or poor ventilation? Based on smell from the bottom of the skirting our issue does seem isolated to the corner of the room which is poorly ventilated so unless it’s dry rot, hopefully if there is a problem it’s not too extensive.

missile

magn8p wrote: »

Great views from your balcony!

How did you cure it by the way?

Thanks, we are very fortunate We were not so fortunate with the builder. The windows were not properly installed / sealed. They had to be removed and replaced.

missile

TheCyclingProgrammer wrote: »

Missile - what was the cause of your damp? A leak or poor ventilation? Based on smell from the bottom of the skirting our issue does seem isolated to the corner of the room which is poorly ventilated so unless it’s dry rot, hopefully if there is a problem it’s not too extensive.

The cause of our damp was water leaking under poorly installed windows.

I hope your problem can be easily rectified. :A