Best way to dry out a house (there are no plugs in the house, so something that can run without a plug ideally)

[James Frome]

Hello

We have bought a house which has had water running through it for a few years (through gaps in the roof). As a result, there is a lot of water-induced damage and rot. We want to dry out the house as best as we can before beginning works in a few months. 

Does anyone recommend a device or devices to best achieve this result? 

The house is around 1100 square feet. 

Thank you 🙏

[Iceverge]

Drying = Reducing Relative Humidity = Heating and Airflow.

 

I assume no more water is coming in?

 

Do you have a fireplace? 

Alternatively a Gas powered heater. 

 

Make sure when you hear the air and it therefore soaks up all the moisture it can escape to the outside. 

 

[James Frome]

Thanks for the response

The house is totally derelict with points of failure in the roof which means during bad weather, water does 'drift' into the house. 

We are renovating the house in around three / four months once we get planning permission. 

1. I am thinking of cheap ways to contain the water entering the house. I was quoted £1300 today to lay some felt under the tiles as a temporary measure. This is quite a lot of money for something that will be ripped up when the house is renovated. 
2. A gas powered heater could work. I am trying to minimise further wood rot. 
3. We don't have a functioning fireplace. 

I was going to get a moisture meter to monitor my progress. Would something like this suffice? https://www.amazon.co.uk/Brennenstuhl-1298680-Moisture-Detector-MD/dp/B003CSNV2Q/ref=sr_1_5?crid=3A3BP92540CBZ&keywords=moisture+meter&qid=1667846741&sprefix=moisture+meter%2Caps%2C77&sr=8-5 

[Roundtuit]

To be honest, I don't think there's any point worrying about it now.  Sounds like a few months isn't going to make a difference to the condition; I'd wait until the roof is sorted.

[Andehh]

Some very large tarps over the roof, screwed down with wood? Not so much dry it out, as stop more rain getting in!

[markc]

If it’s derelict then I presume water has been getting in for some time and a full refurb is in order. In this case you may as well leave it as it is as you will be pulling everything out anyway.

[Temp]

The air is naturally drier in winter so I'd stop water getting in then keep the windows open as much as possible. Theft/squatters permitting.

[Gus Potter]

On 07/11/2022 at 18:31, James Frome said:

We have bought a house which has had water running through it for a few years

If you can post a photo or two.

 

On these ones that are completely done.. It's just the shell you intend to work with.. things we do are:

• On the ground floor make sure any solum vents are clear and free.
• Make sure the worst of the gutters are made leak proof.
• Clear the rain water drains.. if they are done then dig a few channels outside to take the water away from the walls.
• If you have water running down the garden and into the house then look at some French type drain but keep it away from the walls a good bit so it does not cause a problem later on as you develop up the design.
• Kill off any small self seeded sapling trees and other vegitation that is growing near the walls.
• Lift some ground floor boards to encourage ventilation.
• Open all internal doors or take them off.
• If you have sash and cash windows then open them 50 - 75mm at the top and screw so they can't be opened any further, or if windows are broken then board up leaving a 50 - 75 mm gap at the top.
• Cut a few holes in the roof soffit.. if you have one.
• Open up the ceiling under the roof, especially at the corners of the building.
• Ventilate the roof at the ridge. You can just cut a big slot at the ridge, make an small timber A type frame and put that over the top and fix down. The A frame can be water proofed with a wide DPC. In essence it's like a ventilated dry ridge but a lot bigger.

The idea is that you let loads of air circulate at as low cost as you can and even in the winter the place will start to dry surprisingly fast.

 

 

 

[saveasteading]

 

17 hours ago, Gus Potter said:

loads of air circulate

Air flow works much better than dehumidifiers.

[SteamyTea]

Assuming the place is watertight and it is now just a case drying out, then a tiny bit of basic physics may help.

 

Relative humidity is not the amount of actual H₂O in a mass of air, rather it is a ratio of the amount of H₂O that is in the air to the total amount it could potentially contain.  This is why it varies with temperature.

Think of it as a sponge that can hold 100g of water, but is only holding 75g of water, still feels wet.

There are three main ways to get rid of liquid H₂O, physically remove it i.e. find something to mop it up.

Heat it until it evaporates i.e. blow hot air on it.

Change the ratio of dry air to wet solids i.e. dispersion/diffusion.

 

Usually we do the latter two in one cycle, so we heat which lowers the RH, then we disperse it into heated air, that is at an even lower RH.

Now if you cannot easily run a fan off electricity, some sort of natural ventilation will be needed, careful design can increase this.

One way to increase the input of outside air is to have a hole in the wall downstairs, and another hole in the wall upstairs, then add heat near the hole downstairs.  This will reduce the RH of the air in the building, which improves the evaporation rate: evaporation takes place at all temperatures, not just above 0°C.

By allowing the hot air to rise though the building, while being replaced with air from outside (which will almost certainly have a lower amount of H₂O in it), drying will slowly take place.

This is why forced ventilation is used, because if you are only taking out a few grams of H₂O every hour with natural ventilation, it will take a very long time.

If you are on site, or the site is very secure, you could use a portable generator and a gas heater to heat and force the wetter air out.

If the structure of the building is very wet, then it will take a long time, and a lot of energy.

You may be better off making up some clear windows on the sunny side, and let the sun help (wait till March).

Also removing all plaster and getting back to the minimum structure will reduce the amount of trapped H₂O that has to be removed.

If it is a single skin brick building, make sure the wall 'facing the weather' usually the SW side, has good pointing and maybe a waterproof treatment.

 

Purely as an experiment, it would be interesting to put a sheet of clear acrylic over the outside sunny wall to act as a greenhouse.  This could help heat the wall from the outside, while also keeping it dry.  Small vent holes at the top would be necessary.

Edited November 9, 2022 by SteamyTea

[saveasteading]

14 minutes ago, SteamyTea said:

add heat near the hole downstairs

But first try without heat.

There are 2 effects on your side.

1. Stack effect is that air flow at a higher level is usually faster and may suck air up and out if you have high and low vents. A chimney will do the same.

2. Then simply the air pressure at opp ends of the building. Any wind will tend to suck air out.

 

So having holes at all faces, high and low will maximise the effect.

 

The higher vents will also be good in removing warmer, moister air that has risen.

 

Windows and doors do the job as long as you remember to close them again against rain.