Saving an old mill house- advice

[sally ray]

394854394855Not sure if I can post photos here but will give it a shot. On my niece’s New Hampshire property is a sweet little mill house with a (non functioning) water wheel. Inside are antique machinery for turning furniture legs, all run on a belt system that was once connected to the wheel. The problem is the old boulder retaining wall behind the building is moving and pushing into the back wall. I thought she could shore up the boulder and rebuild the damaged wall around the boulder, incorporating it, Japanese style, into the wall. Does anyone have any experience, advice or links to articles where something like this was done?

[Alan Caro]

sally ray,

That's a sweetie! Really a delightful building and setting well worth preserving and putting to use.

I've designed a lot of homes in slope conditions in California, but never a historic structure with a rock retaining wall. Incorporating a rock wall into the structure is a bit complicated to do correctly. It needs to have structural and waterproofing value.

If the slope is more or less parallel to the side of the building, I'd suggest building a new reinforced concrete block wall on a wide, cast footing that is next to and parallel to the side wall, waterproofed, With careful support of the side wall- a good sized lower plate could sit on the top of the new block wall, supporting the exiting /rebuilt side wall and then veneered with boulders so as to hide it. This would mean the interior of that wall would be exposed to the interior of the room and for that, the inside face could again be cosmetically veneered with stone.

It's not too clear as to the angle between the building and the slope , but the way the boulder is pushed into the structure shows there is force along a line parallel to the front of the building. This would complicate things as draining water into the side side of the building is damaging and could eventually push in the wall. In that scenario, consider excavating at least 7' back and building a concrete footing with key, a reinforced block wall with some height above the slope, add a concrete drainage swale behind the retaining wall freeboard that drains slope water off to the side, then add a footing next to the building foundation, dowel that into the existing footings and build another concrete retaining wall about 4' high, waterproof it, veneer it with boulders, then backfill the area between the two walls so it it slopes up to cover a good bit of the upper wall but still leaved and area next to the lower wall that drain slightly back from the lower wall. That should have a French drain with a perforated pipe.

If you provide photos showing the conditions on the side and black of the building- the way the slope interacts the structure, I'd be glad to make more suggestions.

Alan Caro

[Tom M King]

This is some of the type work that I do for a living, but I only work within 10 miles of home, and you are a bit farther than that. Most of it involves figuring it out as you go along.

One thing I do for retaining walls is use block lintels (cast, reinforced concrete to go over door, and window openings in masonry buildings) for deadmen (anchors), to tie the wall back into the hill. I use pieces of steel laid in the wall (sometimes you have to drill holes in stones), as ties, and cabled to the deadmen back uphill. Coat the galvanized cables with waterproof grease before wrapping them back up. I rent a walk behind trencher to cut trenches for the cables, and deadmen, for one reason that it gives a nice straight, undisturbed face to pull the deadmen against.

Even if I was going to do that job, I couldn't tell you exactly how I would do it until we started digging. There are different puzzles to solve every day.

[Peter Kelly]

Where abouts in NH? There’s a shutter company in Center Ossipee that restored an old mill that their shop is currently located in: http://beechrivermill.com/about.php?page=restoration

They might be able to refer you to someone if you’re not far from the Lakes Region.

[William Hodge]

Talk to these people.

https://nhpreservation.org/

(603) 224-2281

The New Hampshire Preservation Alliance can help talk to the right people and help you understand what you have, and how to preserve it for the future.