Drying building (after dry rot)

[victorianjob]

After 5 long months our roof is almost complete and 80% of the repointing has been done so we are almost watertight. Prior to the work the house was empty for 9 years so was in a very bad damp/wet state. Not surprisingly, there was extensive dry rot and we lost entire floors in a couple of rooms. We are now keen to further reduce the moisture levels in the timber and masonry so we can start replacing and rebuilding.

What type of heating/drying method would be best employed? (I know space heaters create lots of vapour) We have a single dehumidifier that we are planning to use and maybe get a more heavy duty one. There is no central heating. Ideally I'd like to use a form of heating that is moveable from room to room. Does a dehumidifier work with drying the wood or will we just be extracting moisture from the air? We have some timbers that have moisture contents or 18-22% (in the danger zone for dry rot) and want to get them out of the danger zone asap.

We don't have any near neighbours so suggested to my Dad and husband that we use a wood burner and move it around the upstairs rooms, sticking the flue out of the window :shock: , to which they suggested I needed sectioning!

Thanks in advance, Cheryl

 

[Owain]

Unflued gas or oil heaters create vapour.

Hire shops have a selection of heaters, which eg run off gas cylinders, but the heater part stays outside (and exhausts the vapour) and there's a big hose to blow warm dry air into the building. The bigger ones will heat aircraft hangers - the only limit is your budget.

Industrial strength dehumidifiers. They extract moisture from the air, them the moisture in the wood permeates into the air, so the wood gets dry. Be cautious about too rapid drying as it can cause wood splits etc.

You can also get blower fans with hoses to blow ambient air into floor voids etc.

 

[Matt Green]

We have some timbers that have moisture contents or 18-22% (in the danger zone for dry rot)

That's far too dry for a fungal spore to germinate on. If there are any hyphae in the timber they might hang on at that sort of moisture content but would be pretty moribund and certainly dying.

I would suggest using cold air blowers, they seem to dry out masonry and timber in buildings more readily than dehumidifiers. Dehumidifiers work best if they are in entirely sealed tents or rooms which is hard to achieve on a site.

 

[Lime]

I completely agree with Matt Green.

 

[Owain]

I would suggest using cold air blowers, they seem to dry out masonry and timber in buildings more readily than dehumidifiers. Dehumidifiers work best if they are in entirely sealed tents or rooms which is hard to achieve on a site.

They're also the cheapest to run, by far.

 

[Penners]

I completely agree with Matt Green.

So do I, particularly as it looks as though the weather is going to warm up. Warm air will hold much more water vapour than cold air.

Just blow the ambient air around and ventilate the building well.

 

[MatthewC]

Even when I thought my house was dry, it has continued to show signs of more drying. Yesterday I noticed that my suspended floor in the lounge shows half an inch contraction since I painted the skirting boards. I guess the joists have shrunk a bit but that was the one room which I thought had remained relatively dry!

 

[robgil]

I would just keep windows open and blow fans on anything damp, lighting the fire is a good way to ventilate.