How to Strengthen an Existing Pier Foundation
A house may be at risk to damage if it has an old pier foundation. The foundation is a fulcrum where the house sits. That foundation secures the house in position. Initially, so that a house is strong, the foundation needs to perfect. Regardless of the strength of the house, if the foundation is frail, a strong earthquake could raise the house from its piers.
The usual drawbacks with posts and pier foundations when there is an earthquake is that the posts tend to move off piers and beams to move off posts. Failure at any of these points could set off the foundation, and at times the whole house, to fall down. But there are things that can be done to strengthen an existing pier foundation. Securing posts to piers and beams is usual process. Lateral brace could be attained by installing 2x4s as diagonal bracket from one post to the other.
A bracing system must give a least resistance to lateral forces for the house. The support must be set up around the border of the structure and, at a minimum, each second line of interior posts, in every direction. Be careful in planning the spaces to be braced so that the braces from each direction do not run into the same post. This kind of support must be regarded as sufficient for temporary stabilization till a stable, adjoining, poured-in-position foundation system is ready to put in. This bracing system could be used for terraces and other outdoor features as well.
Step 1- Set the Forms
Remove the lattice off the spot to be strengthened; set the forms between the current piers. Notice that the earth has been taken off one foot deep (not as much if a solid rock is hit) and put in reinforcing bar before pouring; place fasten bolts into the concrete set.
Step 2- Pour Concrete
When the cement is set, anchor bolt a sill into place, then toe nail the cripple studs into the post under an existing support above. At this time, since the house is attached to a strong load of concrete, it could not jump up from the piers during an earthquake.
Step 3- Nail Plywood
Pin a piece of half inch plywood over the sills and cripple beams. At this point, it would obstruct the house from cutting off or racking if there is an earthquake, like the support of a bookshelf stops it from moving sideways. Finish the task by coating paint.
To avoid damage to the framework of the house, a series of shear walls can be built to strengthen the foundation. Shear walls do not have to be constructed throughout the whole border of the home. It is suggested to construct six walls all in all – a wall on every end of the house (eight feet long) then two walls at every side of the house (six feet long).