21 May 2015

I didn't mean to leave the completion of the steps a mystery, I just sent the pictures to my family and forgot to update here. So, while it still needs newel posts and handrails, the front steps are functional and sturdy. They need to weather for a few months before they can be stained or painted, but naturally I'm in no rush for that.

04 May 2015

Front steps, again

Tom and I got the second half of the top tread off on our own, but we needed help for the next three. Fortunately we have a very strong (and very generous) friend who donated a couple of hours on Saturday to help us get them moved. I plugged the stair dimensions into a calculator online, and it came up with an estimate of about 650 pounds per tread! Luckily, they didn't move very far, just 9' over to outline the edge of the sidewalk. We got them onto a couple of furniture dollies, then simply rolled them to where they needed to go. Once they were roughly in position, we tipped them off the dollies and used a demolition bar as a lever to get them in place exactly.

I'll backfill the area a bit and eventually get some flowers and shrubs in there. Here's what the front of the house looks like without steps:

I dug another trench and laid another row of concrete block close to the wall. The house stayed stairless overnight, but by Sunday evening we had finished the framework for the new steps.

I had already cut all the components and marked their locations, so assembly didn't take very long. A few non-standard construction details: first, I installed 2x4s along the bottom edge of the stringers. I made the treads much deeper than standard treads, which cut deeply into the 2x12 material. The 2x4s simply add additional strength and reduce the stress put on the bottom edge of the board.

Next are the newel posts. I used 4x4 treated lumber, which is standard. Most people will just bolt the 4x4 through the stringers on the end. Those bolts are not the sturdiest connection by themselves, especially when they're only coming from one direction. I added blocking around the posts to add rigidity, then bolted them to the post from two different directions. 

An added bonus to using the blocking is that I could avoid having the bolt heads showing from the sides. And here's a picture of the newel post in place with a couple of bolts in (still needs one more).

The next detail are the back legs, next to the house. The 4x4 posts here are not only newel posts but structural legs that hold up the stairs. They sit on a 2x6, which in turn rests on the concrete block. The 2x6 is bolted to the block, and the legs are bolted to the 2x6 with angle clips. I put a spacer block under the post to raise it off the 2x6 a little bit. If any water sits on the top of the 2x6, it won't get absorbed by the end grain of the 4x4. Just another detail to improve the longevity of the structure.

Now that the structure is set, I can start on the treads and risers, making our stairs usable once again.

01 May 2015

Engineering the front steps

My house is load-bearing masonry. That means that the bricks on the outside of my house are not purely decorative; they actually hold the house up. Similarly, our porch foundation is solid brick. Brick is great in compression, but its shear and tensile strength are practically nonexistent. As a result, attaching stairs to the brick porch foundation is prohibited by code. So I had to figure out the best way to build these stairs and make them safe and secure.

The solution is to build them completely freestanding. Freestanding structures have a different set of rules than ones attached to permanent structures. If I had been able to attach a ledger board to the house (as is typically done with wood-frame buildings), the footings would have to be buried below the frost line, which is about 30" here. This is to prevent frost heave - the movement that occurs when moisture within the soil freezes in cold weather (ice expands as it freezes, displacing the soil around it and forcing it up). Below the frost line, the water within the soil does not freeze, so footings at this depth are safe from that displacement. Frost heave could easily shear the bolts and damage the brick or the ledger board, which is why it is so important for attached decks and stairs to have footings below the frost line.

But because these stairs will be freestanding, they only have to be set on undisturbed (for 5 years) soil. The reason for the difference is that if the staircase suffers from frost heave, the stairs will move as a unit, independently of the house, damaging neither structure. The rise on the final step might change slightly, but not significantly enough to cause problems. That's the reason I only dug about 8" down, tamped down, then filled with gravel and sand before setting solid concrete block. Once I had the foundation figured out, the rest of the construction just fell into place. I'll leave that for the time I actually have pictures as a visual aid.