Posts Tagged ‘Building protection’

Norwegian stave churches: 1000 years old and still standing

11/09/2012

A stave church, or stavkirke, is a timber church with a structural framework of timber staves (beams) resting on timber sleepers and carrying timber wall plates. The wall frames are infilled with vertical planks.

Borgund stave church

The exterior varies from simple and rough-hewn to painstakingly ornate, and in size the churches range from small, shed-like structures – such as Haltdalen stavkirke – to the more imposing Heddal stavkirke, which is the largest of its kind still standing. (At the end of this post, you will find the legend of how the latter was built in only three days.*)

In medieval Norway, the stave frame was the prevalent construction method for churches. There were at least a thousand of them – some sources say as many as two thousand – the length and breadth of the country, built in the 12th and 13th centuries. But by 1650, most of them had disappeared. Following the devastation wrought by the Black Death, many churches fell into disrepair, whilst the Reformation brought a change in the construction, style and use of churches.

Tarred pine shingles clad the steep roof sections

Today, only 28 of the original stave churches remain. Set on stone foundations, the rest of the buildings are entirely made from wood; from the dowels to the roof shingles. It is amazing to see how well some of them have lasted.

The best preserved is Borgund stavkirke in the county of  Sogn og Fjordane, in which most of the existing structure consists of original timbers.

Built from pinewood between 1180 and 1200, it is a striking, darkly ornate structure at the heart of a lush valley. I took the pictures in this post when I visited Borgund last August.

From the interior. In places, rune inscriptions can still be seen.

The intricate carvings, small-format shingles, and black dragons’ heads craning their necks from projecting gable apexes, are miles away from the simple, neutral style we tend to associate with Scandinavian architecture.

Through the centuries, stave churches were preserved by covering the timber in tar. When I visited this summer, the church had just been freshly tarred, making the external wood even darker than normal and lending it a rich, warm scent in the sun.

The external gallery, freshly tarred

The magnificent detailing and impressive longevity of it all made me think of the immense contrast between the church itself and the bleak, sparse living conditions of the people who built it. For farmers and craftsmen eking out a living in a remote Norwegian valley, building such a structure must have been an immense undertaking.

Medieval carvings, beautifully preserved

* There is an old legend about the building of Heddal stave church.

A local farmer, Raud Rygi, wanted to have a new church built. A mysterious stranger came along and offered to do the impossible: to build the church in only three days. His fee for this task was one of three things: either the farmer would have to fetch him the sun and the moon out of the sky, hand him his own heart on a plate, or guess the stranger’s name. Unsurprisingly, Raud chose the third option. He thought he would have plenty of time for name-guessing, as surely nobody could build a church in three days…

However, on the first night, the materials were already in place. On the second night, the steeple was raised. Despairing, and with only one day left before the church would be complete, Raud wandered round the building site at dusk. Suddenly, he heard a haunting voice rising out of the mountain, singing a lullaby: “Hush now, little one, tomorrow Finn will bring you the moon, the sun, and Raud’s heart for you to play with…”

Riddle solved: the builder was Finn, the troll. Raud Rygi’s life was saved, and Heddal had its new stave church.

Runic inscriptions on a church wall

The Old King’s Road, leading up to Borgund stave church

Why aren’t we all enjoying a quiet night’s sleep?

31/07/2012

The introduction of Building Regulations Part E in July 2003 represented a big step by which all residential developments in England and Wales had to undergo pre-completion acoustic tests and meet certain airborne and impact sound performance figures. In 2004, building to Robust Details was added to this, providing an alternative method to pre-completion testing to show compliance with the Part E of the Building Regulations. So – nine years on, is everything as quiet as a mouse?

Patrick Dent, AMIOA MEng and Technical Director of Total Vibration Solutions Ltd, explores the issue of noise.

Image by Romana Klee on Flickr

Have these regulations meant that all new build dwellings and those formed from a material change of use are being constructed in a way that provides no noise issues and leaves each and every resident as happy as the proverbial Larry? Well, the simple answer is no. My weeks rarely go by without speaking to an individual who is having noise issues within their newly constructed apartment or house, yet when we investigate their complaint we find that the development met the requirements of Approved Document Part E of the Building Regulations.

So what’s going wrong? Do we need to revise Part E of the building regs? Are we overlooking certain things in the testing? Or do the regulations simply not give a result that the end client deems acceptable?

In truth, there are a wide variety of reasons why we are still encountering noise problems. One factor that caused a great deal of issues originally – although a lot of developers and specifiers are now aware of this trait of certain materials – was the problem of creep. Acoustic underlays and under-screed materials, which offered good acoustic performance initially, would continue to deflect under load over time and not recover to their original thickness. This would result in the resilience in the floor being lost, floors dropping, and floors that met the pre-completion testing initially, suddenly failing six months later.

This is quite an easily rectified problem that can be overcome by developers and specifiers ensuring that they do not use materials that are susceptible to creep. Foams are particularly prone to creep, so any foams used in this capacity should be closed-cell and cross-linked, however any reputable manufacturer or supplier should have test data available on the creep performance of their materials.

The more complex problems come when we investigate noise complaints where there clearly is a noise problem, and yet the development still passes the impact and airborne tests required to comply with Part E of the Building Regulations.

One such example I was made aware of recently involved some luxury apartments where the occupants had got together and complained that the sound insulation in the floors of their apartments were not good enough. An acoustic consultant was called in to independently test the floors. The results gave on average an airborne DnT,w+Ctr of 50dB (Part E requires a minimum of 45dB for new builds and 43dB for dwellings formed by material change of use, which the apartments actually were in this case) and an impact figure LnT,w of 52dB (Part E requires a maximum of 62dB for new builds and 64dB for material change of use). In other words, figures that any developers would be very happy with, and that were comfortably within the requirements of the building regulations.

However, what the acoustician did notice was the incredibly low background noise level. So although the noise levels caused by people walking above wouldn’t be noticed within a building with a more “normal” level of background noise, in these luxury flats, such dramatic but inconstant changes in noise level makes the sound very audible and quite disturbing.

A lack of background noise makes occasional sounds all the more noticeable

This brings us to the fact that an individual’s threshold of hearing and their perception of noise will change depending upon the environment that they are in. Part E of the Building Regulations doesn’t take the background noise level into account – so in this case, the occupants of these luxury flats are left feeling aggrieved at what they perceive as poor sound insulation in their building, whilst the builders would point to the testing that shows they have more than exceeded the requirements. So who is at fault?

Problems with background noise levels aren’t the only issues that we see on a regular basis. There is a widely accepted agreement that the tapping machine used in ISO 140 does not provide an accurate reproduction of the noise produced by footfall. Similarly, the test does not consider the low frequency performance and given that what you are hearing – particularly in dwellings formed by material change of use with timber floors – is caused by the deflection of the joists induced by the footfall, which produces sound at much lower frequencies than 100Hz, the ISO 140 calculation methods ignore it.

AcoustiCORK™ agglomerated cork underlay for impact noise and thermal insulation

So does this mean that the tests are useless and we should completely overturn them? Well, the simple answer is no. In the majority of cases, Part E provides a very good standard to ensure that the end occupant is not disturbed by noise. But here is where we need to be careful. It is a standard. It is the minimum requirements that a building needs to achieve. Certain circumstances, such as a low background noise level, a higher degree of luxury etc., will dictate that the builder needs to achieve a far greater level of sound insulation.

You wouldn’t fit out the furniture of a student hall of residence in the same way you would million pound apartments. Neither should you treat the sound insulation in the same way.

Copenhagen Climate Conference

21/09/2009
Can the COP 15 delegates reach a CO2 agreement?

Can the COP 15 delegates reach a CO2 agreement?

On the 7th of December, heads of state, advisors, officials, campaigners and media personnel from over 200 countries are gathering in Copenhagen for ‘COP 15’ – the UN’s historic climate change conference.

The aim of the conference is to hammer out an agreement on how to reduce global CO2 emissions.

This is the most complicated deal the world has ever tried to put together,” says Tom Burke, visiting professor at Imperial College and an adviser on climate change to the Foreign Office.

The 'tck tck tck' site asks for a global wake-up call

The ‘tck tck tck‘ website counts down the days, hours and seconds till the Copenhagen conference, providing campaign updates and climate change news from around the world.

ESI information on products that can help reduce CO2 emissions:

The Great British Refurb Campaign

02/09/2009
McCloud campaigns for better insulation (MM Design)

McCloud campaigns for better insulation (MM Design)

Kevin McCloud of Grand Designs is spearheading a campaign to make Britain’s existing housing stock more energy efficient.

• There are over 26 million homes in Britain, most of which are highly energy inefficient.
• They account for around 27% of the country’s man-made carbon dioxide.
• The Government wants to reduce carbon output by 80% by 2050.
• To achieve this target, insulation in existing homes must be drastically improved.

Find out more and join the campaign.

ESI information:
Thermal insulation
Insulated render systems