Questions tagged [subfloor]

Structure above the floor joists and below any finished flooring.

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2answers
92 views

Raising a sunken living room floor and concerned about moisture under new raised floor

I am raising a sunken living room floor but have some concerns about possible moisture problems under this raised floor. Here is what I have. A 1979 typical ranch style. It is roughly a 16 x 20 ...
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1answer
63 views

What size should sistered joists be when repairing a cut joist?

I need to repair a cut joist in my kitchen floor. I was going to use a header and sister the joists on either side of it. Question: how do I know what thickness of a header I should use? What about ...
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5answers
6k views

Can I install heat mat and backer board over cork flooring?

I am installing a new bathroom floor. I plan on getting an electric underfloor heating mat, 2 backer boards for under the heating, screed the mat and tile over this. My question is can I place the ...
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1answer
50 views

Is a gradual 3/4 inch rise acceptable under carpet?

I have a change in subfloor height to contend with. For whatever reason at one doorway of the house the subfloor was built 3/4" (19 mm) higher than the neighboring section. I can install a tapered ...
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0answers
30 views

Should I install a subfloor if I'm putting LVP in my basement?

I live in an area with temperatures from -7°F to 118°F. I'd like to put Luxury Vinyl Plank (LVP) in my concrete basement, but I've heard conflicting reports on if I need a subfloor. Some assumptions: ...
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1answer
65 views

Do I need so many fasteners and an edge gap for a basement subfloor on concrete?

I'm getting ready to install subflooring in a residential basement, which currently has exposed concrete slab. The concrete is well-cured (50 years) with no moisture problems. The plan is to lay down ...
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1answer
71 views

What is this layer of material in the kitchen floor?

I have decided to replace the linoleum flooring in my kitchen with a layer of LVT Underlayment, and then Vinyl plank flooring. There were sections of the original floor that were not covered by the ...
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1answer
38 views

Engineered hardwood over uneven basement subfloor?

I purchased a house 2 years ago with a partially unfinished basement but had all the supplies to finish. I am getting around to doing the flooring soon. I have nice oak engineered hardwood flooring ...
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2answers
68 views

Should I level my basement floor if installing a subfloor?

I'd like to install a subfloor in my basement including that dimple stuff to allow moisture to dissipate. Currently, it has sheetrock walls and trim with painted concrete flooring, but that's it. A ...
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1answer
101 views

Floor sagging between joist- please help

I recently bought an old home- 102 years old and have some flooring issues. The long story is we bought it knowing it had foundation problems in the rear right corner. The home had a poured concrete ...
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1answer
53 views

How to minimize waste when installing the subfloor

I need to replace floor in a shed. Existing floor is a hodgepodge of pieces and materials (flat-edge OSB, particleboard), so I'd like to arrange floor from scratch using T&G OSB. What are the ...
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0answers
34 views

What Medium to Use On Plank Subfloor For Porcelain Tile

Story My wife and I are remodeling our kitchen, and our contractor ask us if we want to remove the hardwood in the kitchen. He said that keeping the hardwood will make the floor solid. I did some ...
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1answer
31 views

If the top layer of my subfloor is structurally sufficient, can I skip patching plumbing holes in the bottom layer?

I'm doing a master bathroom remodel in which all electrical and plumbing must be moved. The old floor had two layers of plywood: 15/32 as the bottom layer, and 19/32 as the top layer. (The numbers I'...
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1answer
45 views

Sub flooring requirements for 2 X 1 rectangle tile

I am about to take on a flooring project and I have never done this before. The previous owner did a DIY flooring job and it's horrible. Cracked tiles and chipping grout everywhere. So as I have ...
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2answers
54 views

Repair/add subfloor plank patch

what is the best way to repair this? the joist is about 24" apart here. what is the best way to add a piece of plank and support it from the joist?
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1answer
151 views

wood plank subfloor repair and leveling

Our plank subfloor needs repair and leveling. Could we do the following: replace some of the pieces add a layer of structural plywood (1/2" or 5/8") on top use cement patch compound to level it add ...
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1answer
48 views

Replacing water damaged Cresdeck D-3

I own a manufactured home and I need to replace some subflooring due to water damage. The current subflooring has a stamp on it, saying it is "Cresdeck D-3". I have some rookie questions to ask: ...
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1answer
68 views

How to level two floors?

I have two rooms with different floor level The wall is removed so now I need the floors to be all level. The higher floor has plywood Should I try to put 2x4 and nail into concrete foundation and ...
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2answers
74 views

Joist design for shed/workshop

I am in the process of building a roughly 12' x 16' shed/workshop. It is going to be a pier-and-beam design. There are 8 concrete piers, 4 on each side, that will support 2 4x12 beams. The span from ...
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0answers
48 views

Installing Plywood Underlayment over Plywood Subfloor

We are renovating an apartment and trying to install a 3/4'' solid hardwood floor in the living room. We pulled out the existing carpet along with a 5/8''particle board underlayment. Under that we ...
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1answer
21 views

Remove damaged flooring under edge of fiberglass tub and direction of new underlayment

I am currently living in my grandmother's old house (built ~1940 or before) where I have yet to find any previous repairs done correctly. The house is a two bedroom, one bathroom mill house type ...
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1answer
71 views

Using shingles to flatten concrete subfloor

I am installing (floating) 3/8" engineered hardwood over a concrete subfloor with 1/8" underlayment. After grinding high spots and filling in larger voids with self-leveler, I have occasional 1/8" or ...
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1answer
50 views

Subfloor tolerance for engineered hardwood

I am installing (floating) 3/8" engineered hardwood with 1/8" QuietWalk underlayment on a cement slab. I have used a grinder and leveling compound to remove the large valleys and hills. Now I have ...
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1answer
72 views

Spider-like / roots? mold?

We recently discovered our dishwasher was leaking under our flooring into the subfloor (formerly the floor - oak before the previous owner added pergo). We’re in the process of cleaning it up and see ...
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0answers
62 views

Preparing plank subfloor for new flooring

I recently bought a house that was built in 1890. Due to the age of the house and some previous issues and general lack of upkeep, the original floors need to be replaced. I plan on laying plywood ...
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1answer
68 views

Proper subfloor for hardwood in a renovation

I'm doing some work on the 2nd floor of a 1955 cape. The subfloor is 3/4" tongue and groove planks and there are 3/4" (maybe 5/8") fir plywood sheets installed over that. The sheets are... odd... ...
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2answers
232 views

Can porcelain tile planks be installed in a crawl space house?

My home is a single story, about 1200 square feet, and is built on a crawl space foundation with a plywood sub-floor. The people we bought the house from had flipped the home after a foreclosure, and ...
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0answers
42 views

Would EVA foam under the carpet (for sound proofing) be a fire risk?

I'd like to put some EVA foam under the carpet (above the floorboards) on the first floor bedroom of my house, to dampen the sound of foot steps. The fire safety building regulations (section B2) say ...
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1answer
76 views

Do I need to replace this sub floor after bad tub installation?

I bought this house ~6 months ago and I noticed then that the caulk around this tub was not installed properly. I just barely got around to opening it up and seeing what was underneath and I found ...
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1answer
28 views

Laying T&G ply sub-floor over existing 1/2" ply sub-floor. What underlayment should i use between the layers?

I am remodeling my master suite. The original floor was 1/2" play (randomly sized pieces looks like offcuts) with OSB over the ply. When we pulled the OSB up, the builder had tarpaper between the ...
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1answer
43 views

Subfloor Water Damage

My wife and I are in contract to purchase a home (not a new home). The inspection revealed a few things and the seller has agreed to fix all but one thing we requested. The one thing they are not ...
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0answers
13 views

LVP underlayment material

I am replacing carpet with LVP in my bedroom, the LVP is going to flow into the hallway (no transition), I need to raise my wood floor 1/2" in the bedroom to match the height of the hallway, can I use ...
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1answer
128 views

yellow zinc plated screw to subfloor and stud

Home is built in California late 1990s. I recently removed some nails and screwed subfloor on 2nd floor to joint/stud below using yellow zinc plated screws from HomeDepot. Now I realized it has notes ...
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2answers
141 views

Edge gluing tongue and groove (non locking) engineered hardwood to make floating floor over existing varnished chamfered-edge hardwood flooring

We wish to lay new flooring above our existing chambered edge flooring. The existing floor is nailed to a plywood sub-floor and is completely flat, about 20 years old. This will make the whole house ...
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2answers
54 views

How to patch small holes in concrete slab basement floor?

I am preparing to install luxury vinyl plank (LVP) in my basement (specifically CoreTec Pro). The subfloor is just concrete slab. Previously this room had carpet with tack strips nailed to the ...
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1answer
47 views

Splintered sub floor under kitchen

Just purchased a new house and found a splintered sub floor under neath our kitchen. Anyone see anything like this? Is it a problem that should be addressed immediately?
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3answers
82 views

Concrete or mud pad below two layers of tile in bathroom. Not sure what it is and whether to demo it?

I recently started renovating one of our bathrooms. After removing a few tiles there was a second layer of tile beneath. Below the second set was a concrete/mortar base that is ~1.5 inches thick and ...
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1answer
92 views

What causes and how to fix lifting floorboard?

It doesn't seem to want to lift up. I assume it is some sort of tongue and groove board because there are no nails or screws anywhere. When I press down on the lifted part with a lot of force it ...
2
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1answer
85 views

Whats the best way to secure a loose flooring joist where mortar has crumbled over the decades?

My kitchen floor sits on joints that are mostly OK. One wobbles though as I walk over it near a wall. It moves 0.5cm (0.25"). I lifted a floor board and had a look. You can see the crumbled mortar ...
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2answers
639 views

New Home - Subfloor soft spots

We recently moved into a new 3-story townhome 4 months ago and are under warranty. Two months ago we noticed a soft spot under the carpet in the hallway of our third floor. We pointed it out to the ...
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1answer
187 views

How do I repair my partially rotted subfloor?

I pulled up the tile in my bathroom and discovered that the sub-floor was partially rotted near the bathtub, under the toilet. Based on the tile/mortar, it looks like whoever did this floor last ...
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2answers
119 views

Tile over 2x6x1.5 T&G subfloor, spanning 48" beams

Long time lurker, first time poster. I think I might have a solution to my problem but I'd like to get some peer review on it before I start work. I'm remodeling a master bath (50sf, 10x5) in a 1966 ...
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3answers
226 views

Plywood repair - subfloor prepartion - subfloor leveling

I am installing 2000 sq ft of engineered wood flooring. Some pieces of plywood are missing portions of the top layer. The plywood is 5/8" for 5 x 1/8" layers - I am not worried about strength. How ...
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2answers
27 views

galvanized hot dipped vs electroplate

I'm considering using nails as an alternative to "backer" screws. The manufacturer recommends "1 1/4" hot dipped galvanized roofing nails" for this application - hardibacker underlayment for bathroom ...
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0answers
51 views

How to install second subfloor?

I'm putting in 12mm floating laminate with a 4mm felt underlayment in my living room and I noticed some bowing in the current subfloor to the point where I can see it while standing up. The high ...
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1answer
43 views

What STAINABLE wood fill is best to use on a plywood floor? [closed]

I am doing a quick fix on an existing plywood, unfinished floor. I need to fill the gaps between boards before staining, then applying polyurethane. I have plenty of Minwax Stainable Wood Filler to ...
4
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2answers
834 views

Second-story floor leveling question for new home

We recently purchased a new home (yes, new construction); the home is a modern-style three story 1800 sqft detached home with a cantilevered section. There's a carport under the cantilever, and then ...
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0answers
118 views

Can I install plywood over a concrete slab to raise the subfloor height?

We bought a house recently. The living room has a slab concrete and tile above it. The kitchen, dining and hallways are above the basement with plywood then hardwood (ugly) then vinyl at the top. We ...
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1answer
63 views

Drilling: what's underneath my subfloor?

I have a squeaky floor and I'm trying to use a kit to screw the subfloor to the joists. However, while drilling to find the joists I can go down less than an inch before the drill stops going down ...
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1answer
62 views

Can you use Rockite instead of Gypcrete?

Can you used Rockite instead of gypcrete to repair a subfloor in a multi-family apartment repair?