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I am in the process of buying a Grade II listed bungalow which has been vacant for the last 4 years. The Building Survey RICS Level 2 (Structural Survey) has unsurprisingly high-lit some damp issues.

To the sitting room wall with rising and penetrating damp to either side of the French doors opening out to the garden.

There is further dampness evident to the sitting room to either side of the chimney breast and the chimney breast itself.

Dampness was evident to the chimney stack in the dining room and also to the walls to the bay window sections.

There is excessive dampness to all walls including penetrating damp to the bedroom.

Penetrating damp and rising damp was evident to the walls adjacent the opening to the bathroom and also the wall adjoining the bedroom/study area.

Further dampness to the bedroom/study extension to either side of the French doors at high and low level with excessive penetrating damp and rising damp to the corner of the wall adjacent the kitchen.

The loft area seems to be fine.

Our mortgage company has requested a Timber and Damp survey from a PCA member which is scheduled to be conducted today. My plan is to carry out any remedial and monitoring work suggested in the report but as this will be a holiday home for my family which will be vacant most week days and used by us over weekends I was wondering how best to tackle ventilation and/or dehumidification as well as drying out the existing damage.

My initial thought is to install a desiccant dehumidifier like the Ecor pro DH1200 DryFan 12L Desiccant Dehumidifier in the roof area.
https://ecor-pro.com/product/dh1200-dryfan-12-litre-desiccant-dehumidifier/
Given this is a listed building I will need to retain the original fabric of the building wherever possible but I do have a number of existing vents or openings to the outside which could be repurposed.

Can anyone tell me if this is an awful idea, if a ventilation system would be better or if I should be thinking of something else entirely?

I have attached a floor plan with as many details as I think would be relevant to help.

Totally understand that the topic of rising damp is highly controversial so if you could please play nicely in your replies that would be fab ;)

Hi tvrulesme
Suggest you reduce the high ground levels to 150mm below DPC level shown in purple on your plan.
Then instal a proper de-humidifier with a permanent drain connection to outside.
Leave things to settle down and damp levels to stabilise.
Regards S

Hi,

First off. If you can I would strongly recommend your survey is carried out by Heritage RICS surveyor not a regular RICS surveyor. Even though surveyors are RICS chartered in my experience they know little, if anything, about period properties. We had a full building survey on our house then later a heritage RICS survey. The difference in the surveys so was vastly different you would think they were of different houses. I have a 200+ year old Georgian cottage and here is some advice I would give you:

> Ventilation is your best friend by far. I have three Meaco whole house dehumidifiers. The are energy efficient and maintain the above ground part of my cottage at 50-55% RH. They only come on periodically throughout the day (so no excessive electricity bill). I also have good extractor fans in all my bathrooms, cloakrooms etc and ensure the vent space if kept clear by periodically removing the fan and cleaning out the debris behind. We have a cellar and since you get penetrating damp (due to it being underground) we have an integrated in line and extract system that brings in fresh air and warms it. Then moist air is removed. Fully automated and keeps a 200+ year old cellar below ground at 55% RH! Also, get some humidistats off amazon (they are cheap) so you can keep an eye on the humidity throughout your house. Research by English Heritage, Historic Scotland, SPAB say that 'little if any damp issues will be present if Heritage properties are maintained at 50-55% RH and above 15 degrees Celsius.' once your house is 50-55% RH in most rooms you will find most issues will go.


> Keep external ground levels below the internal floor level ideally. This will stop penetrating damp from outside coming in.

> Try if possible to not use any modern materials on external walls (including the interior side). Examples of this include masonry paint (which it looks like you have on your gable wall), cement render (outside), gypsum render (inside), repointing of bricks in cement etc. These all trap moisture into walls as they are not breathable. The problem is that older properties are designed to breath and move (as they are build on shallow footings). In an ideal scenario all inside external walls should be lime plastered and painted with breathable paints (I recommend Keim mineral paint). However, I would only make these changes IF there are problems caused by the misuse of these materials. My previous owners painted part of the house and also gypsum plastered some internal walls but since I have no damp issues from these I am leaving them for now. I strongly recommend you keep an eye on the masonry paint on the outside walls. If it starts to bubble, crack, peel etc then that means moisture if trapped inside. If you leave it in this state too long the delicate period brickwork will spall. Is you get excessive spalling this can be a very expensive endeavour to remedy as the only solution is to lime render the property. If the masonry paint is intact then leave it. If/when it needs removing ensure the people you hire use the DOFF system as sandblasting is too abrasive for period properties.

Sorry for such a lengthy reply. I love period properties and could go on typing for hours! Drop me a line if you need anymore advice.

DIY_Guy wrote:Hi,

First off. If you can I would strongly recommend your survey is carried out by Heritage RICS surveyor not a regular RICS surveyor. Even though surveyors are RICS chartered in my experience they know little, if anything, about period properties. We had a full building survey on our house then later a heritage RICS survey. The difference in the surveys so was vastly different you would think they were of different houses.....

Can't thank you enough for this. This is scarily close to what we have planned so I'm really pleased you're put my mind at rest with a lot of this.

So we got a timber and damp survey done and fortunately the guy really understood old buildings. His first question to me was "do you want this building to be air tight like a new build? If so I would walk away as it's never intended to be this way".

I'm a bit of an old hat in home automation so sensors and monitoring are going to be key here. Will be putting temperature and humidity sensors in each room with a rad, install "smart" TRVs on each radiator and constantly monitor and adjust to keep the room temperature above the dew point. I'm going for a semi-permanent install of a Desiccant Dehumidifier in the loft area venting to the rooms which will be triggered when the humidity rises above 53%

https://www.machinemart.co.uk/p/ecor-pro-dryfan-12-dh1200-12l-desiccant-de/

In terms of outside ground levels, exactly what you have prescribed. Drop to 150mm below floor levels wherever possible and a DOFF chap is going to bring it back to brick. Will repoint where needed with lime mortar.

Thanks for the recommendation for paint. I was edging towards Earthborn but will get some Keim mineral and compare.

So glad you said the bit about re-plastering IF things don't improve. This is what I was planning but have never seen this backed up by someone who has done it.

You're welcome. Enjoy your new home. Everything you have outlined in your plan of action sounds good to me. Yes the IF is very important. Someone experienced in the trade e.g. a lime plasterer will probably tell you to what they told me which is to re-plaster every inside external wall in lime as they are a perfectionist and also drums up business. The heritage surveyor we had was excellent and had 25+ years purely surveying heritage houses all his life. He said only fix unsuitable materials when they cause a problem. He said he rarely goes into a period house where the owners have done everything using the correct materials throughout. So he said definitely don't re-plaster any of the walls in lime as there were no damp issues.

I would be cautious of your survey in how literally you take it. The surveyor makes reference to rising damp. This term is a heavily debated term and most of the experts see it as a misnomer. The English Heritage is such an organisation who doesn't believe it to exist. It's thought that every 'rising damp' issue is attributable to some other underlying cause rather than it being 'rising damp'. See this for some good background reading - https://www.youtube.com/watch?v=Jo8oF9u ... lZTPqVXjcx. Also, how has he assessed the 'damp'? Damp meters don't work on masonry and are not designed to. That being said RICS surveyors still use them. A specialist surveyor will do carbide testing and this is really the only way to tell if masonry is damp. It involves drilling out some of the brick itself and measuring it's water content. We had this done in our cellar as the initial survey flagged the cellar as being 'very damp' with 'high damp readings throughout'. When we had the heritage surveyor come he did carbide testing and said there is no dampness in the masonry at all. The dampness seen was residual surface water from penetrating damp and just needed better ventilation to get rid of it. This may also interest you on damp meters:

https://www.youtube.com/watch?v=tea3uknHOVc

Have fun with the new house!