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-   -   pinning brick walls? (http://www.diychatroom.com/f19/pinning-brick-walls-52394/)

harperkc 09-06-2009 04:00 AM

pinning brick walls?
 
I am getting ready to buy a home that was built in 1894 and it has some movement on outside brick pulling away from inside brick layer. I have recieved a bid to place 7 pins at different locations on one wall. I don't really understand exactlly what pinning is and just how difficult of a job is it? the walls seem to be two layers(inside and outside) with an air gap on the middle is this normal for that time period? Thanks

Daniel Holzman 09-06-2009 08:45 AM

From your description, you have what is known as a double whyth brick wall, meaning there is an inner and an outer brick layer, separated by an air gap. This type of construction is still used, however it is more expensive than the more common veneer brick construction method often used. With veneer brick, the brick is connected to a wooden framed wall using brick ties, which are steel strips nailed to the wooden inner wall, and which extend part way into the brick on every third of fourth course of brick. The ties strengthen the wall, and reduce the chance of brick movements.

In a double whythe construction, brick ties are used to connect the brick walls to each other. The ties are installed during the mortaring process, and if you are getting movement of the outer wall, chances are the ties were either installed incorrectly, or have corroded to the point where they are no longer functioning correctly. Ties can only be installed through the mortar, and due to the geometry, the normal process to replace ties is to take down the outer wall, install the ties, and rebuild the outer wall by mortaring the ties in place. The same can be done by installing new ties into the outer wall by removing the inner wall.

An alternative is to drill through the brick, and install pins. I have never seen pinning done in the field, perhaps one of the masons on this site is familiar with the process. The advantage would presumably be that you don't disassemble the wall, you work with it in place. The ties would need to be either expansive anchors or some sort of epoxy, again I have not seen the technique actually used, I am simply reporting third hand about the method.

harperkc 09-06-2009 10:59 AM

Thank you Dan for your reply and it's nice to learn that they still use the same building method today as in 115years ago. This is a four story house so taking down the brick and rebuilding is not really an option:-(. What bothers me most is that the estiment for the pinning was only 1400.00 dollars. So if there's a mason out there let me know what you think.. Thanks Harper p.s. will close on house sept 17th (still time to run:-)

Tscarborough 09-06-2009 12:22 PM

I don't know of any structural brick double-wythe walls with an air gap. Those are 2 different systems of masonry construction, and veneered brick over structural masonry is relatively new. In older structural masonry, there is no air gap and the brick are tied longitudinally with other brick, not metal ties. If this is the case, it is easy to detect: Are there 1/2 or 1/3 bricks in the pattern or is it a simple running bond?

Regardless, pinning the brick involves either predrilling a small hole or using a self drilling tie that looks like a twisted ribbon to tie the brick together. Either way, a structural engineer should be involved.

jomama45 09-06-2009 01:02 PM

Quote:

Originally Posted by Tscarborough (Post 324416)
I don't know of any structural brick double-wythe walls with an air gap. Those are 2 different systems of masonry construction, and veneered brick over structural masonry is relatively new. In older structural masonry, there is no air gap and the brick are tied longitudinally with other brick, not metal ties. If this is the case, it is easy to detect: Are there 1/2 or 1/3 bricks in the pattern or is it a simple running bond?

Agreed, it may be a regional thing, but I've never seen the use of metal brick ties in a brick double wythe wall from that era. I don't know how well mild steel of that era would hold up to the lime in the mortar either. A double wythe in my area would generally have a header (all ends of brick showing) course every 6 courses. The first floor of the home would be 3 or 4 wythe, with the header course spaced farther apart, as the tie-in brick are alternated between exterior & interior wythes. The walls generally lose one wythe per story going up.

As per the air space, i've never seen a clear airspace, nor a fully slugged wall. Any inteded air space would be terminated every 6 courses by the tie-in brick the way the buildings were generally built here.

To the OP, do a google search for "American Bond", as it be an indicator that brick were used to tie the wythes together.

Regardless, pinning the brick involves either predrilling a small hole or using a self drilling tie that looks like a twisted ribbon to tie the brick together. Either way, a structural engineer should be involved.

I'm glad Tscar has experience in this field, as I've never actually seen how this was done.

The only major movement I've seen in these style homes is due to foundation movement.

harperkc 09-06-2009 04:44 PM

1 Attachment(s)
I am attatching a picture of house.. there seems to be no on end layers of brick (except for turrit) would there be another way of attaching wythe walls?? Attachment 13319

Tscarborough 09-06-2009 06:16 PM

That looks like a straight veneer to me. I would not touch that house with a 10 foot pole.

stuart45 09-06-2009 06:30 PM

This is a common problem in the UK as the majority of our homes are cavity wall constuction. The older ones are brick/2 or 3 inch cavity/brick. The idea is to prevent damp penetrating the inner wall. When the ties rot the thicker types can expand by 4x their thickness and lift the brickwork. You can see the cracks in the bed joints. The ties normally rot at the top first as this part is the most exposed to the weather.
In the 60's we used to take down the outer skin and rebuild, but in the last 30 years specialist companies use Helix ties which can be inserted as mentioned in the previous posts to save rebuilding. However when the thicker wrought iron ties were used some bricks have to be removed to enable the ties to be taken out. When the thinner butterfly ties were used they can be left in.
Looking at your house I would say that some of the brickwork will need rebuilding, but it's hard to be sure from a photo. However houses with wall tie failure in the UK, usually have all the ties replaced, as even in the more sheltered walls there is usually some signs of rot in them. The SE will always drill holes in the external skin and use a fibre optic camera to check the condition of the cavity and ties. Just replacing 7 ties doesn't sound like it will be enough of a permanent solution, so I would get someone to check the condition of the cavity.

Tscarborough 09-06-2009 06:45 PM

Stuart, when were those houses built? I am guessing after 1930.

stuart45 09-06-2009 06:56 PM

The first cavity walls in the UK were built around 1850 in coastal areas. They became more common after 1900, depending on the area of the country. The 9 inch solid brick wall was still the favorite. In 1936 the Public Health Act meant that all 9 inch solid walls had to be protected against penetrating damp by something like render, tile hanging or shiplap timber, so the cavity wall became the popular choice. Nowadays the most common type is brick exterior/ 4 inch cavity of which 2 inches is insulation board/ and then 4 or 5 inch aac blockworkwork.

Tscarborough 09-06-2009 07:07 PM

I see. The philosophy of the 2 systems is totally different. In the traditional structural masonry wall, it is expected that there will be moisture penetration, but that the wall mass will prevent the penetration entirely through the wall, season to season. The veneer or barrier wall system also acknowledges that the moisture will penetrate the veneer, but is designed such that the secondary, or backup wall will repel the moisture, and the airspace will provide an avenue for the moisture to exit the wall through weeps, and be contained by flashing.

In the United states, the veneer system is very rare before the 1930s. It is almost unheard of in a building dated 1894, and this, added to the fact that the brick has a 99% chance of being laid with lime mortar that is now painted, is indicative of a very serious problem.

At the best, it can be pinned, at the worst, the veneer will have to be removed, the backup waterproofed, and then a new veneer laid.

No way would I even look at buying this house, much less attempting to repair it.

stuart45 09-06-2009 07:21 PM

I wouldn't be rushing out to buy it either. There looks like a lot of work on the external walls alone. Plenty of jobs there for the wife to nag me into doing, taking away my valuable pub time.


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