Structural Wall Surgery

While the extending the floor, I was somewhat simultaneously re-framing the only remaining Victorian-era structural wall left in our flat so as to accommodate an opening for the new bedroom door. This door location is only possible because of the floor extension - the new door is squeezed in between the top of the old staircase, the kitchen and the beginning of the new staircase that goes up to the loft.

Perspective from 3D computer model used in the design phase - the new bedroom door and new staircase (upto new loft) meet at this critical location adjacent to the new kitchen

This arrangement was developed in the design phase when it became apparent that in order to open-up the space, yet maximize the size of the kitchen and bathroom, we would have a very tight convergence at this very location. This convergence makes the floor extension and relocation of the door critical to the new layout. At the time it was not obvious this wall was structural (it supports a post that helps hold part of the roof) but having worked previously on this wall, and reviewing the proposed work with building control, I felt confident moving forward.

March 27th - The original Victorian-era structural wall (plaster was removed during demolition)

The "surgery" involved cutting through the existing studs to create an opening that will fit the future door. As in all structural work of this kind, the most important thing is to brace the areas of the wall that are doing the structural work so that the wall does not "know" that you're re-arranging it - it's almost like a magic trick. If the structure realizes what you're doing...you're in trouble...

So the first step is to brace the beam at the top of the wall (known as a wall plate) that is actually carrying the weight of the roof post above it (that helps support the roof). The brace is rather simple - a heavy stud (old growth wood from the original roof) that sits on top of temporary beams that span the opening in the floor for the stair.

The temporary brace to support the wall-plate while structural work occurs

Once the brace was in place, I began to cut away at the studs and re-frame the wall to accommodate the opening. Because this wall is one of the bedroom walls, I did this work keeping the plywood sheathing in place, since the plywood acts as the temporary walls to the bedroom, keeping the dust out. But this made the work more difficult, so I had to go "old-school" and use a handsaw...

Cutting and removing the first pieces of the wall

Using a handsaw at a tight spot where power tools would not fit

The opening is done and new side studs repositioned...all that's left is horizontal member at the top of the door opening

Once all the members that were in the way were removed, I was able to reposition the vertical studs (doubling them up on one side for more strength) and then finally add a double "header" at the top of the door opening. A header is the horizontal member at the top of a door - because this wall happens to be structural, this header is structural and will do the primary work of transferring the weight, or "load", of the roof post to the rest of the wall.That's why the header is doubled up and additional vertical members are added using steel clips to ensure their position and strength.

Once everything was in place, I held my breath and removed the temporary brace...all is good!

The brace is removed and the newly re-framed door opening is complete

Before & After montage. On the left (before): the structural wall and floor - On the right (after): the extended floor with the new door opening

Extending the floor

After almost a month in New York, I'm back in London again. Now that the shower is finished (!), I'm going to shift my efforts towards finishing the remaining "heavy construction" so that we can try to wrap up the major work by the of the summer.

What that means is that I'll now be focusing on the preparations for the new staircase that will eventually go upto our new loft & dormer. This will include:

• Extending the floor so it meets the correct location of the new stair. Besides adding around 15 sq ft to the overall area of our flat, this extension will also provide the necessary floor area to locate the new door into the bedroom (currently, "The box"). So this extension is critical to the new layout & design of the flat.
• Re-framing the structural wall (adjacent to the staircase) so that the new door into the bedroom can be opened.
• Once the structural wall is re-framed, it needs to be sheathed in structural plywood and then covered in "fire-proof" plasterboard (1hr rated to be precise), as per the instructions from our council's Building Control officer.
• Build and install the landing for the new staircase - it needs to be built first because it will help hold up the stairs...also, it will give the stairs something to frame into
• If the above items go well...start building the staircase...!

The existing staircase (down to the flat's entry door), with the structural wood wall next to it

Before extending the floor, I needed to open up the existing floor and determine the exact location and level of the new beam that will carry the new floor area as well as the new staircase. Because this is the only remaining area of the floor that was not leveled, the contrast (between the old sloping floor by the stair and the new leveled sub-floor) became quite obvious...with a difference of over an inch!

Morning of March 26th - the existing conditions and original end of the floor.

Sub-floor removed, exposing the joists underneath

The level shows the extreme difference between the old sloping floor/joists and where it should be so it's level.

Because of the extreme slope of the old floor, I realized that it will be necessary to reconfigure the top of the stair to get everything level. This required pulling off the top step so as to fully expose the beam below. Once the joist was fully exposed, I was able to set-up a string line and determine the future leveled location of the new beam.

Removing the original top step to expose the beam below

The string line and level - note the difference between the string (which is level) and the slope of the old floor/beam!

The location on the structural wood wall were the new joist will go. Removing the plaster to expose the wall plate below where the beam will sit. (A wall plate is a horizontal stud within a wall - usually in between floors)

With the location of the beam determined, it was time to create the openings for it to go into and determine the structural support that will hold it. On the side of the exterior wall, I cut into the wood trim and exposed a wooden wall plate that holds the joists (the wall plate sits on top of the brick wall below). On the other side (at the structural wood wall) I also found a wooden wall plate that was conveniently at almost the exact location I needed to sit the new beam on. Once everything was opened, I cut the new wood beam and inserted it in place. It took some time to set it at the exact level, but I was eventually able to get there.

Afternoon of March 28th - locating the wall plate that will hold the new beam (at the exterior wall) and establishing the correct level there. This required a thin steel plate to get it to the exact height needed.

The new beam at the correct level (notice the difference between it and the old beam)

Once the beam was set to the correct level, a second beam was cut and they were fastened together (this is known as sistering) to create an extra strong beam. This double beam was then fastened to the old, sloping beam to help stabilize it and prevent any further settlement or sloping.

The double beam fastened in place

Now the fun part started...I was able to remove the old railing and start setting up for the actual floor extension. This again required using string lines to determine the correct location of the new joists (that will frame into the double beam). Once everything was worked out, I was able to to cut the wood and install special steel clips (called joist hangers) that help make the structural connection between the joists.

Morning of March 29th - The new double beam in place...then removing the original railing.

String lines locate the positions of the new joists.

With everything cut and the joist hangers in place, I was then able to insert the new joists and fasten everything together. Within a few hours they were structurally sound, and i was able to add a layer of plywood so we could walk on our new extended floor!

The joist hangers in place, holding the new joists

The completed framing

Adding a piece of plywood so we can walk on it...

Floor Leveling: Day 1 - Demolition

Today we started the process of leveling the floors. As in many old buildings, the existing floors are slightly wavy, so when doing this degree of renovations it's usually a good idea to make the floors level. Because the original floor boards appear to have a lot of character, we're hoping to re-use them. That's going to cause more work, as we'll have to carefully remove them, take out all the nails, and then at the very end of the project, put the boards back down and refinish them. But re-using the boards will allow us to save wood and should hopefully retain some of the character of the old boards.

The process of leveling the floors begins with clearing the floor of everything, then removing the old boards one by one. Once the boards are removed, the floor joists will be exposed and we'll be able to establish the level using strings and a small water-level. (The danger of open joists is that one must be careful to walk only on the joists otherwise you could risk putting a foot through the neighbor's ceiling!) The string over each floor joist shows the distance that it's off from level, so that distance is filled with a strip of wood. Each piece has to be custom cut, so it's a slow and tedious process. Once all of the strips are in, we can start fastening sheets of plywood down for a sub-floor. That sub-floor is safe to walk on and ultimately will have the finish floor boards nailed to it. Here, I'd like to ultimately install a 2nd layer of plywood but put a roll of sound absorptive material to help minimize the noise transmission from the floor.

Clearing and cleaning the floor of everything

Removing the old carpet sub-floor boards to expose the original wood floors

The original floor boards

Montage of flat with original floor boards exposed

The guys: Jimmy, M, and yours truly (from left to right)

The first few floor boards out

One can now see the rafters - and the neighbors' ceiling

Roof Construction: Open Heart Surgery - Day 2

Today we continued with our open heart surgery on the roof. It's Saturday so we are required to stop at 2pm today...a lot to do with limited time...

Yesterday we opened up the lower portion of the roof's corner and installed the bottom two steel channels. Today, we're opening up the rest of the roof which means that 1/2 of the entire roof will be open to the sky. These next few days will be the greatest exposure of the flat to the elements. Once the roof is open, we'll have to measure the remaining lengths for the top two steel pieces, cut the steel and install them to reinforce the hip rafter and splice them together.

This sounds much easier than it is--for starters we have only one shot to get the correct cuts in the steel and cannot make any mistakes. So we ended up cutting small bits a time to get the correct angles and geometry. We ended up going back and forth half a dozen times before it finally fit, but at least we got it. Because it took so much time to cut the one piece, we'll have to cut and install the final piece of steel on Monday.

Interior view in the morning

The upper half of the roof slates removed - you can now see through the roof!

The ends of the lower two pieces of steel

Interior montage - half of the roof open

Cutting ends of one of the upper steel pieces (this happened 6 times)

Finished end

Bringing the steel onto the bridge (this also happened 6 times)

Lifting it into place (this also happened 6 times)

Once the steel is correctly in place, tightening the splice (connection)

Fastening bolts at the splice

Looking out from the open roof

2pm - covered-up and finished for the day

Roof Construction: Open Heart Surgery - Day 1

Today begins the most intense and dangerous phase of the entire project...and of course the weather is terrible. Fortunately I knew it would rain (because I've been looking at the weather forecast obsessively) and built a temporary roof over us.

Our temporary roof

Today we're doing the equivalent of open heart surgery: we're ripping open 1/2 of the entire roof at the corner; cutting out the structural support of the hip rafter (corner roof beam); removing all the rafters attached to the hip rafter; and inserting a new steel channel on each side.

These channels are around 4 meters (12ft) long and are probably the heaviest items we've had to deal with so far. Because things have been going well with Jimmy and our two Romanian day laborers, I decided to do this work ourselves rather than hire the Polish crew, who had become somewhat difficult to deal with--and quite expensive. I was nervous about doing this, but have been starting to feel much more confident about what we have been able to accomplish ourselves. I guess this will be the ultimate test!

The reason we're going through all of this is to be able to remove a structural wall that's supporting the hip rafter at the midpoint. The hip rafter is the corner beam that all the other rafters are attached to - it's like the spine. In order to open up the living area and remove this final wall, we need to be able to compensate for the wall's support once it's gone. To do this, our engineer specified two heavy steel channels that will sandwich the original wooden beam. The steel will provide the necessary stiffness, but there has been a significant amount of grumbling from the guys that this is over-engineered. In this case I do agree with them, and I had tried to get the engineer to change the design, but he refused. So we were left without a choice, and we've had to build the bridge in the living room and will spend the next few days doing what will probably be the riskiest work of the entire project.

Removing the first few slates at the corner

Almost enough removed to start work on the steel

Cutting the post that supports the hip rafter!

The view from inside the flat

Separating the rafters from the hip rafter to make space for the steel

Inserting the 1st piece piece of steel

Getting it to fit - not much space to work with

The 1st piece of steel in place

Inserting the 2nd piece of steel

Setting the clips that will hold the steel in place

Both beams in place

Today we were lucky. Everything went much better than expected, and considering the risks involved, I'm feeling relieved and more confident that we can finish this phase without incident.