Interior Dry line with Humidity

reddle28

Hi,
I live in a 1960's bungalow that i bought 2 years ago. The house has 3 bedrooms, a bathroom and kitchen and dining room. It was built with cavity walls (approx 75mm). Before I moved in about 2 years ago I replaced all windows and doors, insulated attic, pumped walls with beads, and dry lines the right hand side of the house, which is the living area. Since i moved in the house has been quite humid, For example yesterday eveining it was 82% @ 19.0c, day before it was 75% @ 19.8c. It does get lower but also gets higher depending on heat, time of year, windows open etc, i would say avarerage is about low 70's. The floors are suspended wooden floors sitting about 1.5 feet above ground. I have not been able to root cause the humidity problem - the ventilation in the attic from facia and sofit is good - the vents under the floors are not block and seem good, the new windows are vented - the bathroom and kitchen have extraction fans - im not losing water from radiator pipes and even when i removed the floors and inspected underneath everything looks fine.
I have a baby due to arrive (first) in 5 weeks and as a result i have builder coming in the morning to dry line the remainder of the house, the three bedrooms. My main worry is the effect of dry lining over what potentially could be the problem, the walls. There currently is no mold appart from a very small few specs at the top corner of one bedroom....will the dry lining make the humidity worse?....does anyone have any advice on where the moisture is coming from??
By the way - the house is at the top of a hill and also i have 3 chimneys, 2 are in use, i have checked them from the attic and they look dry...but i have not sealed them outside with anything, also i often use a de-humidifier, it works and reduces the humidity but once it is turn off the humidity rises again.

reddle28

Hi Lads,
Anyone have a little help or advice on this one.

Thanks.

archtech

I would recommend you engage an arch tech, architect or other professional with retrofit skills/experience to do some analysis. I note you haven't mentioned if you are hole in the wall vents in each room, this could be part of your problem.

reddle28

archtech wrote: »

I would recommend you engage an arch tech, architect or other professional with retrofit skills/experience to do some analysis. I note you haven't mentioned if you are hole in the wall vents in each room, this could be part of your problem.

Hi thanks for your reply, I may have to contact an architect, however, I was hoping I might get info here also, anyway in relation to your comment on the holes, I was of the opinion that these holes would ventilate and reduce humidity?

BryanF

the need for a humidifier concerns me, i lent out my RH sensor so I'm not sure whats happening with our current weather but anything above 80 indoors is not normal.I agree with archtech above, you need help (before & during builder visit) and it sounds like a ventilation issue, maybe you should enquire about positive input ventilation or a variation of this. however you should also close of the possibility its a damp issue, so check the usual culprits, external ground levels reletive to suspended floor, DPC, window or eaves or crack letting in water etc etc. before dry-lining further check existing dry-lining and ask builder to lift a section or two of floors. maybe buy a damp sensor first and hunt the house looking for increased moisture levels. best of luck, with your moisture issues and first born!

BE_MIEI

You said that the timber floor joists are 1.5 feet above the ground, is the external ground level below the ground level under the suspended timber floor? If it is not, you could have a sump effect in the subfloor void. This could be your source of moisture.

reddle28

BE_MIEI wrote: »

You said that the timber floor joists are 1.5 feet above the ground, is the external ground level below the ground level under the suspended timber floor? If it is not, you could have a sump effect in the subfloor void. This could be your source of moisture.

Hi,
I think the external ground level is a little higher than the sub floor, but I have lifted boards and there does not seem to be any damp underneath. Im think of drill 2 x 4 inch vents at the front of the house where the humidity is highest, this is north facing, do you think this will help, unfortunately I'll lose heat from them

archtech

A Demand Control Ventilation System could work for you but unless you can establish the source of the problem it may never be solved and there could be long term effects that have serious implications on the building fabric as well as health.

DOCARCH

reddle28 wrote: »

Hi thanks for your reply, I may have to contact an architect, however, I was hoping I might get info here also, anyway in relation to your comment on the holes, I was of the opinion that these holes would ventilate and reduce humidity?

Hi reddle28, you didn't really confirm whether or not each room has a permenant air vent? This ventilation should help reduce humidities.

I doubt the dry-lining is the cause of the high humidity levels and I also doubt that you completing/carrying out further dry-lining will solve the problem.

As suggested above, there is obvioulsy a source of damp somewhere within (or under) the structure. Have you access to a damp meter? If not, you could rent one and check all internal and external walls, above floor level, all round the house to see if the source could be from rising damp?

I was working on a house recently with a suspended timber floor and there had been a small leak in the incoming water main, probably for years and years, and it had caused the sub-floor to be damp - the resulting dampness was coming up through the floorboards in one room causing the room itself to feel damp.

reddle28

Hi Docarch,
Thanks for great reply, I have no vents in the rooms apart from the window vents which are approx 10mm diameter holes x 15 per room, maybe this is not enough. What do you think??, I was considering drilling 4 inch vents in the 2 north facing rooms. I have checked under the suspended floors numerous times but it looks none dry. How reliable are the moisture meters??

gilmac

Have you looked at PIV positive input vetilation this could solve your problem.