How do I fit a weather bar and drip to an external timber door?
What each of the three pieces at the bottom of an external door actually does, in which order water meets them, and why a weather bar fitted the wrong way round makes the problem worse.
- Difficulty
- intermediate
- Time
- 1 hr
- Read
- 4 min
Short answer
A weather bar is a sloped bar fixed across the outside face of the door near the bottom, throwing water clear of the joint. A drip is a groove or a projecting moulding under it that stops water tracking back. A threshold and seal deal with what still gets past. Fit them in that order, outside in.
The bottom of an external door is the wettest part of the building and it is where timber doors die. Three separate details fight that water and most doors have one or two of them at best. Understanding what each one does makes it obvious which is missing on your door.
What you'll need
- A weather bar to suit the door width
- Exterior-grade sealant
- Stainless or brass screws
- A router with a small cutter, or a purchased drip moulding (optional)
- Exterior primer and paint or an exterior wood finish
Step by step
- Work out where the water is going now.In heavy driving rain, or with a hose used gently from a low angle, watch the door. Water running down the face and then under the door means no weather bar. Water tracking backwards along the underside means no drip. Water arriving over the threshold means the threshold detail is wrong.
- Understand what each part does.The weather bar throws water off the face before it reaches the bottom joint. The drip stops what does get there from running back along the underside by surface tension. The threshold and its seal are the last line and they only work if the first two have done their job.
- Check the door swings clear.A weather bar adds thickness to the outside face near the bottom. On an inward-opening door it sits above the threshold and must clear it as the door swings. Offer the bar up and swing the door before fixing anything.
- Set the height.Low enough that water shed from the bar lands outside the threshold, high enough to clear the threshold as the door swings. Usually just above the bottom rail. Mark a level line across the door face.
- Prepare the timber first.The face under the bar will never be reachable again. Prime and paint or seal it before fixing, and prime the back of the bar too if it is timber. A bar fixed onto bare timber traps water permanently against it.
- Bed the bar in sealant and screw it.A continuous bead of exterior sealant along the top edge line, then fix with stainless or brass screws at regular centres. Tool the sealant along the top edge so water runs over it and not behind it. Leave the bottom edge open so anything that does get behind can drain out.
- Deal with the drip.If the door bottom or the sill has no drip groove, one can be routed into the underside of a projecting sill, or a purpose-made drip moulding fixed. On a door, a groove in the underside of the bottom rail is the traditional detail. It must be continuous and it must stop short of the ends.
- Check the threshold and its seal.The bottom seal or brush sweep on the door, and the weatherbar or threshold section on the floor, are the last defence. Replace a flattened brush, and make sure the threshold sheds water outwards rather than into the floor build-up.
- Paint everything, including the underside.The underside of a door is almost always unpainted and it is where water enters end grain. Take the door off, or wedge it open and reach underneath, and treat it properly.
- Recheck with water.Hose the door gently from a low angle, mimicking driving rain. Watch inside for anything arriving. Repeat after the sealant has cured properly.
Common mistakes
- Sealing the bottom edge of a weather bar as well as the top — Any water that does get behind then has nowhere to go and sits against the timber permanently. Seal the top, leave the bottom open.
- Fitting the bar without painting behind it — It creates a permanently damp, permanently inaccessible strip of bare timber across the wettest part of the door.
- Running a drip groove right to the ends — Water then tracks out of the groove ends and down the reveal. Stop the groove short of each end.
Questions people ask
Do I need a weather bar on an outward-opening door?
Less so — an outward-opening door closes against the frame's outer face and the water path is different. The critical detail there is the threshold and the seal, and often a drip over the head.
Aluminium or timber weather bar?
Both work. Timber matches a painted door and can be replaced easily; aluminium lasts longer and is the usual choice on a stained or oiled door where a painted bar would look wrong.
My door has a weather bar and still leaks. What now?
Check the drip and the threshold, then check the door's own joints and the frame. Water can arrive at the bottom of a door from a failed joint two-thirds of the way up.