Screw the sill down or not?

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Old 06-19-18, 07:37 PM
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Screw the sill down or not?

I've seen videos that recommend attaching an exterior door sill with screws to the subfloor. However, I just removed my old sill and only found concrete block under the sill. I was planning to mix up some concrete and create a solid, level, and sloped surface for the new 2" oak sill. I suppose I could use concrete screws, but I'm wondering if I really need to screw the sill to the floor if it's already solidly attached to the jams?
 
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Old 06-19-18, 07:58 PM
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I've never screwed down a sill that was attached to jambs. It needs to be properly supported with a sill pan underneath to prevent moisture infiltration. I just replaced an exterior out swing door that had the sill screwed down. Aside from the jamb rot, the screws were also totally rusted out. The wood that was under the threshold was completely rotten and had to be replaced. Went with an inswing door with a storm door to add splash security given the proximity to a drip line off the gutters.
 
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Old 06-19-18, 10:14 PM
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The original was rotten, but it was over 100 years old. I wasn't aware of a sill pan. Do you build one or buy one and where?
 

Last edited by guit-box; 06-19-18 at 10:52 PM.
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Old 06-20-18, 03:29 AM
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I'm not sure if you use a sill pan with a wood sill...do you Z? Lord, if it's done even slightly wrong the sill will be sitting in water all the time, won't it?
 
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Old 06-20-18, 07:18 AM
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I had Siwek Lumber build me the wood sill. It's a 2" slab of oak that has 4 surfaces angled so the resulting sill is sloped about 7 degrees -- I think. It's mortised/screwed into the jams which have fiberboard at the lower 6". It looks identical to the 100+ year old one that's at my front door. As far as I can tell, there's only heavy tar paper under the front door, but if there's a better modern way to do it, I'd like to know. There is no wood under the sill in this case, it butts up to a floor joist but the sill will end up being only over the concrete wall. (which is crumbling and will need to be built up and leveled with concrete so the sill fits smoothly on top of it.)

An internet search shows two options of sill pans.
1. galv sheet metal that needs to be fabricated
2. a lap joined pvc type that is glued like pvc

Everyone seems to use a membrane tape around/under the sill pan

Edit: I just called Siwek and the older gentlemen there said he'd never heard of a sill pan. This place has a huge wood shop that builds replica doors/frames like mine. He said I don't need one. Thoughts?
 
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Old 06-20-18, 10:41 AM
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I just bought some Tite Seal: Self adhesive waterproof flashing, and I think I'll use that under the sill and verticals. I'm sure a sill pan is better, but no one I've talked with at the home store or the professional builder place sells them or thinks I need one so it's probably overkill. The previous sill lasted 100 years and if it lasts 1/2 that I'll be gone by then anyway, haha. If I'm overlooking something please let me know, I want to do it the right way, but I also want to be reasonable.
 
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Old 06-20-18, 02:40 PM
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I'm not sure if you use a sill pan with a wood sill...do you Z?
Most all new sills are aluminum with composite support members underneath. Will never rot, the purpose of a sill pan is to prevent water infiltration into the house by creating a dam that sheds water away from the inside and back into the outside.

I must have read this wrong if you are going with a custom wood sill. I assumed that this was a complete door unit replacement.
 
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Old 06-20-18, 03:00 PM
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That's what I thought...to prevent water penetration. And I caught the "2" oak sill".
 
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Old 06-20-18, 05:19 PM
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So, no sill pan with the 2" oak sill then?

I just made a form and created a sloping concrete slab that matches the bottom slope of the wood sill. My feeling is that with the waterproof membrane and all the sloping, it will be way more waterproof than the original.
 
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Old 06-20-18, 05:27 PM
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All you need is sill sealer on an old fashioned sloped sill.
 
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Old 06-20-18, 05:35 PM
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Thanks for the info, I'll go with the membrane then.
 
 

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