Insulating solid walls of a Victorian house

Insulating solid walls of a Victorian house

This is the last post of a three part insulation special! We’ve covered the easiest ways of insulating your Victorian house, now it is on to the hardest job. Insulating solid walls!

This was almost the post that wasn’t to be. There is lots of information about insulating the walls of period properties and most of it points towards leaving the walls alone. Insulating is often more trouble than its worth.

It really isn’t easy to insulate the walls of any house. It is messy, very disruptive and depending on how you do it will usually mean losing a significant part of the room. Even with the  slimmest of insulation your will lose valuable centimetres off the perimeter of your room. Fine for Victorian mansions, not so fine for two up two down Victorian terrace houses.

With period properties insulating solid walls is particularly difficult. Extreme caution needs to be taken! The first thing to consider when thinking about insulating the outside walls of your house is do I really need to do this? Once you have adequately insulated the loft space and the floor of your home it might well feel warm enough.

It is potentially disastrous to insulate a solid wall home. It really is! You need to be very careful how you approach this. It can lead to all kinds of problems. You can lock damp into the walls behind the insulation. This will eventually damage the brickwork. It will also cause mould and damp.

The outside brick work can also suffer and perish. Without any heat from the inside of the house permeating to the outside brickwork, this can leave the outside surfaces damp and cold. A damp house is a cold house. This is the most important thing to consider.

If you are in any doubt leave well alone. Victorian houses were designed to be heated most of the day. The inside bricks warm up and stay warm as long as there is low level heat. This heat then keeps the house warm and dry. This is exactly the same way storage heaters work.

It also offers some protection to the outside of the property. After heavy rain fall the heat from inside the house will dry out the brick work. Any insulation from the inside can stop this heat from warming the outside of the property and eventually cause damage.

You may also be part of a terrace. If you are sandwiched between two houses then it is likely that you won’t need wall insulation. When you’ve installed the floor and the roof insulation wait for the first really cold week in winter and see how it performs. I like the house about twenty degrees. Nineteen and and I’m wearing a jumper!

If a house could easily be heated to this level without wall insulation on the coldest days, then I would be happy to leave well alone. I’m sure this would be the case in smaller terrace houses. I lived in one for about five years of my life and I don’t remember it being too bad. It would heat up pretty quickly when the heating was on and we had single glazed windows. It was always dry. I never saw any mould.

However, this could be entirely different in a bigger property. This is something that really should be considered when you purchase a house. A large Victorian houses with no insulation will be very difficult to heat in winter. Or rather very expensive.

The loft as we’ve been through is an easy fix but the floor will take time. The walls will take even longer. It won’t be cheap either. If it is a detached property it’ll be even more expensive. With at least twice as many walls to the outside. You may need to insulate every outside wall to get it to stay as warm as you want without running the central heating all day and all night.

What it will never be is waste of time and or money. If you plan to stay in the house for a few years you’ll get your money back. Maybe not in capital gains but definitely in comfort.

So lets assume you wish to insulate the walls, lets see how best to do this. Firstly, I’m only going to explore inside walls. Insulating the outside of Victorian houses isn’t usually permitted. It would change the look of the house dramatically.

So there are a couple of different ways of doing this. You can if you’ve got walls in really good condition add a small amount of breathable insulation to the inside wall. You really need to be sure that your walls are in perfect condition. Dry and undamaged.

If your walls are already damp then they will need treatment first. This could also solve your heating problem. After the walls have dried out it could well be that you don’t need to add any extra insulation. It has been said so many times that dry equals warm. It is very difficult to warm up a damp house.

To dry the walls out you are going to need to strip off whatever it is that is causing the problem. It could be wall paper, modern paint, modern plaster, cement render or a combination of all of those things. Get expert advise. Proper expert advice! Contact companies who specialise in period properties.

Once the problem has been identified you can start fixing it. If the walls need stripping back to bare brick then get ready for some disruption! Skirts and features will need to come off. Taking the plaster/render off is something you can do yourself. It is very messy and it is also hard work. If you do the work yourself you will save a fortune.

Insulating solid walls

Once this is done and the wall is clean any repairs have been done you can add heat to the room to dry it out. With all of the brick work exposed, you’ll quickly be able to warm up the entire fabric of the wall which is great. The air quality will improve, any smells will vanish and you have a blank canvas to work with.

It is at this stage that you can decide what to do. If it was my house I would use hemp and lime plaster. The hemp is an insulating material and is completely breathable and then use lime plaster over the top of this. The hemp is put on by hand onto the bare walls. It is a lengthy process but it actually looks fun!

Insulating solid walls

Lime plaster is the best choice as this is also breathable. Sadly its more expensive. I don’t think you can put a price on a warm dry comfortable house. I couldn’t. It is one of the most important things for me.

Another product that would work well is a thin covering of wood fibre and then lime plaster. This is also breathable and will really help to keep the warm air in. The key is not to use too much insulating material. 50 mm of wood fibre is all you should be using.

You have to except that you will never achieve modern levels of heat retention in a Victorian property. Not through the walls anyway. Some of the warmth has to reach the outside wall. The moisture has to escape. Your home must breath and be adequately ventilated.

So in conclusion leave the walls if you can. The floors and loft can be insulated to modern standards and this should do the trick. If you have problems with damp in your walls then strip them back and add a small amount of breathable insulation. Use lime plaster and breathable paints. You have to accept that there will be some heat loss through the walls. There actually has to be. The buildings were designed this way. The old saying of if it isn’t broke don’t fix it has never been more appropriate in this situation.

Next week I will be looking at Hallways. See you then!



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