retaining wall and stem walls to help support roof

Job ID: 37020899

Budget: $250 – $750 USD

We are looking to hire a structural engineer to design a plan so we can build a retaining and stem walls to help support my side porch roofs and also repair the damage from frost heaving to my lower deck and one of the upper deck support posts. These structures will be constructed from reenforced concrete, including a 10’ retaining wall, a stick built two story atop the 12" stem wall and footing, and replacing current roof post supports with stem wall structure. The purpose of the project is to provide structural support to the porch roofs and front decks to prevent frost heaving due to snow melt in the spring. I am looking for a structural engineer with knowledge and experience in construction and the usage of the materials mentioned.

We live in NE WA state 30 miles from Canada. We have built our home in stages. The porch roof supports were done in 2005. We used 18" Sono tubes for base support for the roof and deck, no extra concrete footing just placed on compacted fill. Now they are shifting due to water and freeze thaw.

We believe we need to add footings, 12" stem walls, more drainage, relevel the porch roofs and enclose the side decks so the weight of the porch roofs is dissipated across a much larger area. The roofs support has sunken on each end (pictures 4 and 5) Currently the porch roof sits on large log posts (approximate 12" in diameter) on top of 18" diameter concrete reenforced with rebar, that was poured in Sono tubes. The base was compacted but no extra footings were installed.

The main part of the building is 30' wide X 40' long. The wrap around porches on the side have a 7' cantilever overhang in the front and a 5' cantilever overhang in the back. There is an 18" overhang on the porch. The pitch is 3/12 on porch, 8/12 main home. Building material is logs 12" minimum.

There is underground water on one side of the home. French drain is in place.

We believe all of the problems are from the drip lines of house (no cutters) and water flow from spring melt coupled by improper grading of soil and improper drainage material used the rock retaining walls, have moved about 2' (picture 3) need to be replaced and proper drainage and fill. The stem wall may be used in order to ensure the proper grade for the water to flow away from the home.

This porch project is being done with the deck project.

One of the front lower deck posts has frost heaved out pulling the upper deck support out at the bottom (Picture 1) and some of the lower deck joists are sitting on the dirt (picture 2). We need to support the upper deck, while we realign the post that has frost heaved out, after we remove the lower deck. There is a retaining wall in front of all of the other posts and they are on very large footing, 18" concrete round bases, all rebar reenforced concrete, with at least 12" diameter log posts.

We have removed some of the deck boards, and pictures are attached to show what has happened. We are prepared to remove all fill (mostly dirt), add more drainage fill, pipe, and replace with all drainage fill compacted and put a concrete cap with a 5% slope (more if necessary) so snow melt from top deck will not pool behind the retaining wall and cause frost heaving.