[BeeEmmDubleYuu]

We moved into a new built house around 3 years ago. The ensuite room has a patio door with windows and a shower in the other room.

The shower has an extractor fan which turns on only when the light is switched on. As soon as the light is off the fan switches off.

Every year what I notice is damp around the wall by the patio/windows and in the shower room there's damp by the window. First year I told the builders who came and applied some substance around the patio which stopped the damp appearing.

Now a couple years later I'm finding the same issue again. Slight damp appearing around the patio and in the shower damp around the window.

I spoke with the builders again who say they cant do anything about it as its a condensation issue. I appreciate they may have applied cheap paint and that we may need to repaint with appropriate bath paint but what I need to know is if this sounds normal? Or what I could do to stop this from happening?

In short our house warranty with the builders is coming to an end soon so I want to be sure the work they have done is at an acceptable level and that nothing has been missed off.

If this sounds normal then what could I do to reduce this issue? What substance could be applied to minimise damp and what type of paint should be used?

Generally we go for a shower and open all the windows for at least 30 mins but its annoying as in a new house I didn't expect this type of issue when we never had it in our previous older house.

Appreciate any thoughts/advice.

[John320d]

More air changes are the answer to this problem. Get an electrician to fit a timer to your showerroom fan and instal an airbrick.

[MAN15H]

My en suite was fitted with a timer controlled extractor fan since it was first built but the room still suffered from a little damp so I brought a dehumidifier and that solved the problem.

[Igotwood]

I'd say you have 1 of 2 options, either get an extractor fan with a humidistat and timer, or replace your current extractor with one with a higher flow extraction rate

[rogerxp]

Can you leave the window locked in the vent position? This should help keep air circulated. Dehumidifier has helped us with condensation on the windows. Basically need to get that moist air outside - damp towel, water evaporation from shower, drying clothes, etc, all contribute. Modern houses seem to be too insulated & air-tight they cause these issues!

[rogerxp]

...I did just think, our new extractor fan in our main bathroom is on permanently, but on a very low setting (virtually silent). When you switch the light on, it goes into 'boost' mode which remains on for 5-10 minutes after the light is switched off, then settles back down in low mode. Helpful for permanent gentle extraction and air circulation.

[briers]

Our latest house is our newest build but it doesn't have a filled cavity it has insulating block on all internal walls and room dividing walls.

We actually got lazy with our extractors and opening windows because we never get condensation or mould which I can only assume is because the cavity can breath.

Last house mould and condensation was common. Simply left all vents open and opened windows during and after shower and extractor stayed on 5 mins after light off. Still didn't completely solve the issue.

Therefore no plans to fill this cavity.

[doughboy]

OP, to be building regs compliant the extractor should have a delay on it. It really should stay on for at least 5-10 minutes after the light goes out.

It will have an in built adjustable timer and it seems like it has been turned down by someone.

[BeeEmmDubleYuu]

Originally Posted by doughboy

OP, to be building regs compliant the extractor should have a delay on it. It really should stay on for at least 5-10 minutes after the light goes out.

It will have an in built adjustable timer and it seems like it has been turned down by someone.

Do you have any reference i could use to tell our house manufacturer? At present it doesn't have a built in timer to leave the fan on after turning off the light. I did check this with them and they confirmed there's no built in timer.... So ideally i would like to go back to them with some evidence?

[doughboy]

House manufacturer?

Unfortunately modern houses are shit.

They are built out of cheap materials, by idiots on a budget.

Every aspect is usually bodged, or poor quality, of bad workmanship etc.

I would forget the NHBC crap and the halfwits they will send out. Take control and get a decent, personnally recommended, electrician out to fit you a new extractor and make sure it runs for 20 mins after light out.

[BeeEmmDubleYuu]

Originally Posted by doughboy

House manufacturer?

Unfortunately modern houses are shit.

They are built out of cheap materials, by idiots on a budget.

Every aspect is usually bodged, or poor quality, of bad workmanship etc.

I would forget the NHBC crap and the halfwits they will send out. Take control and get a decent, personnally recommended, electrician out to fit you a new extractor and make sure it runs for 20 mins after light out.

NHBC??

Although i agree with you i just want to ensure that they have met all criteria that i may not know about. We purchased the house through Persimmons so it could mean they pay for it and the electrician i choose as so far they have been helpful if theyve done something thats not correct.

[doughboy]

Sorry I thought you were claiming on the NHBC 10 year guarantee thing on new build homes. Had bad experiences of that scheme.

Ok, if you're dealing with builders direct that might be better.

When was it built? building regs change all the time and The builders will only honour the regs in force when it was built.

[BeeEmmDubleYuu]

Around 2011..... So i don't know what standards they should have met but very keen to know

[doughboy]

Sorry for delay....

Attached here is the Building Regs section F for ventilation, in force since 2010.

Page 24, go down to "Controls" then "Intermittent Extract" then bullet point 4 covers.

A 15 minute overrun is only required on rooms with out any openable windows (i.e. internal room). On such a room the light switch may be used to switch the fan on.

So if you have a window, the regs and therefore the design of the house assume you will leave it open to ventilate the room.

Does the room have any natural light? If it does, then strictly speaking they shouldn't use the light switch as you don't need the light in the daytime, so the fan wouldn't come on as required. If it has a window or natural light then they should use a PIR detector to operate the fan, not the light switch.

New houses can suffer a lot with condensation as they are much more airtight than older houses and have less natural ventilation (i.e. drafts!).

To be honest, the slow speed at which the damp marks are appearing seems more down to lack of cleaning (no offense meant). Just general good maintenance, cleaning and wiping of walls should keep it at bay, and high humidity rooms need this more often anyway. I know we wipe our bathroom painted walls every few weeks with mild anti mould spray keep marks at bay, especially round window frames etc where cold air causes more condensation.

But you need a good paint on the walls, cheap crap magnolia builders paint won't last 5 minutes.