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U-Values in the spot light…at last!!

The environmental winds of change may be finally changing directon in favour of traditional buildings.

Last Tuesday I went to a seminar in Birmingham entitled Old Building Energy Efficiency Research. The event was organised by The Society for the Protection of Ancient Buildings (SPAB).

This seminar was very timely and brought together various pieces of research currently ongoing into heat loss and energy conservation of traditional buildings.

This topic is important for those wishing to protect and preserve our architectural heritage because the current eco-philosophy states that “new is good and old is bad”!

Let’s get rid of all the old houses and build lovely new eco-homes. Yeah, great idea…not!! Have you ever walked up 4 flights of stairs on a summer’s day and entered into a new build flat!!

My philosophy and the cornerstone of this blog is to preserve what we have and with a few sensitive alterations, make the older buildings more energy efficient. Sorry, but to me that just feels right.

For the real eco-boffin the key measure of a building element is the U-Value. The U-Value measures the rate at which heat passes through the external envelop of the building for each 1o C of temperature difference between the inside and outside temperature.

The external envelop could be a roof, wall, window or floor. It doesn’t matter what the particular element is, because with the standard U-Value calculation we can now compare one element with another. We can also compare different types of the same elements too, e.g. a solid brick wall with a cavity brick wall.

Now here’s the thing!

What if the U-Values are wrong!!

Okay, not wrong but a little out or even a little too theoretical…no, silly idea really sorry I shouldn’t have mentioned it. Those clever people who live in laboratories must know what they’re doing surely!!

Well, the speakers at the seminar think we should start being a little more cautious with the current set of U-Values for traditional building elements because what they’ve found is that U-Values for traditional building elements are often significantly underestimated.

This effectively means that traditional building elements often have a better U-Value than the standard U-Value data used in RdSAP software. This software is currently being used to calculate energy performance Ratings in domestic EPCs and will be the basis by which Green Deal recommendations are generated!

Eureka, I’m not mad!!

Finally, we’re getting some clarity and some empirical data that proves what a lot of people have thought for years. Well done to Archimetrics, English Heritage, Historic Scotland and the SPAB!!

You can read the research and follow the case studies by going to the SPAB website.


High quality brickwork repairs and authentic air vents

The brick corner after repairs

The back of my house has been neglected for many years. My recent restoration projects have focused on the large more complex work such as the windows and roof coverings.

My latest project has been the cast iron soil and vent pipe and since some bricks were damaged during its installation, I thought it might be a good idea to get a really good brick restoration specialist in for a couple of days.

I was made aware of a company called Mathias Restoration who undertook brickwork repairs to some very good quality and high value property in North London. Lynn Mathias came down with a young colleague and started work. To say I was impressed was an understatement. Their work was exceptional and of the highest quality.

Brick corner before repair work started

They started worked on areas that had either become worn or weathered or had been damaged by drill holes or opened up for ventilation purposes. The after works photo speaks for itself.

However, one problem with getting the bricks repaired by Mathias Restoration is that it makes other areas of brickwork look shabby! I’m sure they’ll be back in the New Year for some more repair work.

An original cast iron air vent of the “Y” pattern

Choosing air vents…

Having started to look at the brickwork on my house, I’ve also started thinking about the air vents used for sub-floor ventilation. Most of the air vents around the house are the clay brick type which are completely serviceable but not authentic.

As a bit of background, the air vents are used to remove water vapour under the suspended timber ground floors. The through ventilation created by having air vents at the front and rear of the house allow moisture from the ground under the house to escape. If the timber floor joists have a moisture content above 18%, wood boring insects become active and if the moisture content rises above 20%, timber decay becomes an issue.

Now fortunately, I’ve still got two original cast iron air vents on the house, so the other night I did a bit of digging on the internet for suppliers.

An example of an original Y6 cast iron air vent from 1906

To my great surprise I came across the Cast Iron Air Brick Company and to my even greater surprise found exactly the right match. Although they’re more expensive than the standard air bricks, for the restoration junky who can’t compromise, they’re a must have accessory to a fully restored brick wall.

Check out Mathias Restoration and The Cast Iron Air Brick Company for yourselves.

Cast iron soil pipes will last a century if painted regularly

View of old cast iron pipe with rusted rear curved section.

The soil and vent pipe (SVP) is the pipe that allows flushed waste from the toilet to enter the foul drainage system. On older houses these pipes are made of cast iron and often painted black.

The problem with cast iron SVPs is that they’re very difficult to paint along the curved sections facing the brick wall. Over many years the unpainted cast iron will rust and eventually create a tiny hole. The hole will allow foul water to run down the outside of the pipe and then enter the property through the brickwork, resulting in internal dampness.

My cast iron SVP has been leaking for some time and today was the day that a new cast iron SVP was installed. It’s tempting and very much cheaper to have a plastic version installed, but plastic components of any description are banned in my house!

The photo above shows the thinner section of cast iron that has just rusted away to nothing, for lack of regular painting. However, where the pipe has been painted the metal is in excellent condition. This proves that regular maintenance ensures components such as SVPs last for many years, if not centuries!

My plumber ordered the two 2.00m sections of cast iron pipe and with some effort and a few cups of tea managed to insert the two new sections back into place.

I am now going to make sure that the whole section of pipe is cleaned up and repainted in gloss black, ready for another 100 years of service.

Cement render entraps moisture against a solid masonry wall

Sketch showing damp pathway through the solid masonry wall.

I inspected a property recently and thought you might be interested in the dampness caused by cement render entrapping moisture against the masonry wall.

Internally, there was evidence of moderate levels of dampness but nothing serious. However, prior to my arrival a remedial damp company claimed the dampness was rising damp and therefore expensive remedial work was required which included chemically injecting the walls and blar, blar, blar…you know the rest!!

However, when inspecting the wall from the outside it was clear that there were 3 more obvious reasons why the wall was damp:

1. The external ground levels have been raised. This shortens the distance between the surface rain water on the ground and the dry masonry above the damp proof course.

2. The external render has been taken down to the ground. This bridges the damp proof course and allows surface water to become drawn up the narrow gap between the render and the brickwork.

3. The cement mortar render is hollow. This allows surface water to migrate up the narrow cavity formed when the render and the masonry wall de-bonded.

The damp pathway is now complete!

When it rains any surface water is sucked straight up the narrow gap between the render and the masonry wall, bridging the DPC and making the internal surface of the bedroom wall damp. See my sketch above.

Removal of the hollow render revealed the dampness behind.

During my inspection I got permission to remove the hollow render which I did with the blue shovel. The render just fell off in large sections and revealed the band of dark masonry at the base of the wall which confirms the bricks were damp.

The photo was taken immediately after removing the render. The sun was shining that afternoon and since the wall was south-west facing the dark damp band of brickwork, visible at the base of the wall and which had reached 5 brick courses above the line of the DPC, dried within 10 minutes!

I recommended to the owner that the ground levels should be lowered to at least 150mm below the damp proof course and the rest of the render removed and the wall repointed with a lime based mortar.

This approach to dampness is in full compliance with BS6576: 2005 part 4. This however is in stark contrast to the remedial damp company who confirmed rising damp before establishing whether there were any other reasons why the wall was damp. I therefore saved the home owner a large amount of money from unnecessary remedial work.

FRONT DOOR FRAME – Before and after restoration

Finished door frame and stained glass

After some years of persistence I have finally got the front door side panels and transom window finished.

I have posted several short articles on each stage of this transformation but thought you might like to see the before and after photos.

I still can’t understand why anyone would deliberately remove the original details and effectively replace them with bland featureless glass and trim. Anyway, I have now got it back to somewhere near its original design.

Door frame when the house was bought

The front door is the next big project and I have someone in mind for this job. The company lined up is K&D Joinery Ltd of Dagenham. They have already made an identical door for a similar house nearby, so I’m hoping this can be commissioned in the near future.

If you’re wondering how I got the nice warm glow of light through the glazing. I placed an Anglepoise lamp in the hall with a 12W compact flourescent lamp aimed at the door.

1 leaded glass panel completed

The first completed panel of glass incorporating the 8mm reeded glass and the roundels.

As promised I’ve just taken charge of the first of 10 leaded glass panels for my front door. The leaded glass was made by Michael Fennelly of East Finchley.

They incorporate the, impossibly difficult to obtain, 8mm reeded glass (mentioned in my previous post) and those fantastic roundels mentioned in the post before.

I hope you agree it looks pretty good and worth the wait. I like the red glass inserted as a margin between the reeded and the English Muffle. This makes the piece more vibrant and also matches nicely with the piece of stained glass in an adjacent window.

Finding original glass for window repairs

Genuine 8mm reeded glass in a leaded window

When undertaking repairs to leaded or stained glass windows you’ll quickly find that the old types of glass that are used to decorate Victorian and Edwardian houses are no longer available.

In my previous post (Where to buy authentic glass roundels), I mentioned that specialist glass artisans can make small individual pieces such as the roundels, but for authentic sheet glass, it’s a case of either trying to find a modern equivalent or tracking down some old panes from glass merchants.

I struck gold some weeks ago when I tried to find some original 8mm reeded glass for my front door panels, see photo for an example.

The 8mm reeded is no longer made so you have to either use the modern 6mm or 10mm reeded, which has a different look and is a poor match.

An original piece of English Muffle glass

I’m now on the hunt for some English Muffle glass which again is no longer made and can only be obtained by finding old pieces of glass, see photo opposite.

With regards the panel I’m having made up, I’ll hope to have a finished glass panel to show you in a few days…