Deck Repair and Making Sense of What's There Now

[AdrianeS]

My front porch has almost half of the boards rotting along with what's underneath it. I'm posting pictures here in hopes that someone can help me figure out how best to fix this. I'd like to tear it all off and replace it but when I pulled off some of the rotten boards, I found more boards underneath (also rotting) rather than the joists I was expecting. I can see the joists from the ceiling in my basement and thankfully they look good. However, when I look at the ceiling in the basement (below the porch) I can't tell if I'm looking at the bottom side of the boards that are rotting, or if this is another layer of flooring.

I'm hoping someone can help me understand how my porch was built. Why is there a subfloor underneath my tongue and groove porch? Would I replace this as well or can I do without it? I'm considering composite decking but this needs space between the boards for drainage and I'm not sure that's compatible with a subfloor. If I do away with the subfloor and install the new porch over the joists, the porch would no longer be even with the entryway and there would be about an inch or so step down. I'm not sure what to do about that either.

Any thoughts or ideas appreciated!

 

[Snoonyb]

As a point of orientation, does the damaged sub/floor run parallel or perpendicular to the floor girders, and what is the girder spacing?
How is the deck flashed where it intersects with the dwelling?
In the 3rd photo, the 4s "J" box should have the conductors safe'd off and a blank cover installed.

You are correct about composites, besides which they require in the field, periodic fastening.

 

[Eddie_T]

The house I was raised in was a story and a half with a full width front porch. The porch was floored the same as the house, tongue and groove oak flooring over a board sub floor. It was somewhat protected in that it had walls (maybe 3' high) with what we called a banister board on top. I had never given it any thought but there was no provision for drainage.

The house was over crawl space but floor framing plan was four 16'x16' ft squares with joists running parallel with the front and board sub flooring. The porch was just an open room rather than being an addition like a deck. I am thinking that houses with basements had porches over a portion of the basement. We had a small porch on the rear that was just inset into the corner of the house off the kitchen. We had it enclosed and called it a breakfast room though we ate most of our meals there.

 

[Eddie_T]

I see that it is definitely not a deck but is a small entryway porch inset into the corner of the house. That being the case you don't want any drainage between boards to the basement. There may be some sort of weatherproofing between the layers as I see no indication of leakage on the basement ceiling. The ceiling doesn't look like sub flooring. Has it been cut and inserted between joists? Is it the same under the front room to the right of the porch (basement pic view). Being small replacement may not be so daunting if you can remove enough material to get a clean view of the original layers.

 

[AdrianeS]

As a point of orientation, does the damaged sub/floor run parallel or perpendicular to the floor girders, and what is the girder spacing?
How is the deck flashed where it intersects with the dwelling?
In the 3rd photo, the 4s "J" box should have the conductors safe'd off and a blank cover installed.

You are correct about composites, besides which they require in the field, periodic fastening.

Thanks for your reply! That box is not connected to anything right now, those wires aren't connected on the other end, I'm in the middle of doing that now.

The damaged subfloor runs perpendicular to the girders which are 18" on center. I can't see any flashing whatsoever, the house (and most likely the porch) was built in 1923.

 

[AdrianeS]

I see that it is definitely not a deck but is a small entryway porch inset into the corner of the house. That being the case you don't want any drainage between boards to the basement. There may be some sort of weatherproofing between the layers as I see no indication of leakage on the basement ceiling. The ceiling doesn't look like sub flooring. Has it been cut and inserted between joists? Is it the same under the front room to the right of the porch (basement pic view). Being small replacement may not be so daunting if you can remove enough material to get a clean view of the original layers.

I should have titled it "porch" and not "deck". I don't think the ceiling looks like subflooring either, and yes, it is the same on the the other side of the porch. It also does not look like it's been cut and inserted between the joists. It is a small area, only 8x8.

 

[AdrianeS]

The house I was raised in was a story and a half with a full width front porch. The porch was floored the same as the house, tongue and groove oak flooring over a board sub floor. It was somewhat protected in that it had walls (maybe 3' high) with what we called a banister board on top. I had never given it any thought but there was no provision for drainage.

The house was over crawl space but floor framing plan was four 16'x16' ft squares with joists running parallel with the front and board sub flooring. The porch was just an open room rather than being an addition like a deck. I am thinking that houses with basements had porches over a portion of the basement. We had a small porch on the rear that was just inset into the corner of the house off the kitchen. We had it enclosed and called it a breakfast room though we ate most of our meals there.

My house sounds very similar to that. My porch is the same oak tongue and groove boards that are throughout the rest of the house. The strange thing is, that there is no subfloor whatsoever on the inside, the boards are run directly over the joists. Which is another reason why I was so surprised to find a subfloor underneath my front porch.

I'd still like to know how my porch was constructed, just how many layers of material are there under the tongue and groove before I get to the joists? I'm really not sure how to go about repairing this. All the info I can find is for porches built directly over the joists.

 

[Eddie_T]

Another consideration is the integrity of the joists and the support column at the corner. Ideally everything would have to be removed down to the joists and replaced with new material. If joists are sound then one could begin at the wall and proceed until near the column then install a temporary support, remove the column (or jack up slightly) and floor up to the corner. Then the column could be repaired or a new one constructed depending upon condition.

I am wondering with the house having uniform joists and flooring how the porch flooring can differ from the house? It would appear that the same joists (basement view) would be running under the front room to the right (if I am visualizing correctly) or at least as far as a center beam.

Caution! I am not an expert so just use my comments to assist your thinking.

 

[Snoonyb]

Thanks, I would venture to say that under the subfloor you see from the removed material, you will likely find some form of roofing material, acting as a pan, and if so, I'd be hesitant about removing further, because there are modern materials which may better serve your reconstructing the deck.

 

[Eddie_T]

It's hard to visualize the construction. The porch may have smaller joists on wider centers than the rest of the house as there is no X bracing between joists. If the house doesn't have sub flooring then all hardwood flooring would have to be installed perpendicular to the run of the joists but that could still leave tongue and groove end joints unsupported which seems unlikely. If you have sub flooring then the flooring in all rooms doesn't have to run in the same direction. We're missing something here so don't make any hasty decisions. This may not be a homeowner project.

 

[Eddie_T]

I found some clues. Hard wood floors nailed directly to joists were 7/8" thick and boards were longer. They were installed perpendicular to joists and more board ends could be seen aligned when looking across the floor. If floors were laid parallel to joists spacers were added between joists at 16' intervals. This was early in the 20th century later hardwood flooring was reduced to 3/8" thickness and installed over sub flooring.

I read where some porch flooring was installed over sub flooring with a layer of tar paper. This Old House made mention of some use of a lead caulk to waterproof tongue and groove joints when over basement or crawl space.. This is my speculation but to achieve the same level for porch and interior floors maybe shallower joists were used to accommodate the extra material.

 

[AdrianeS]

Another consideration is the integrity of the joists and the support column at the corner. Ideally everything would have to be removed down to the joists and replaced with new material. If joists are sound then one could begin at the wall and proceed until near the column then install a temporary support, remove the column (or jack up slightly) and floor up to the corner. Then the column could be repaired or a new one constructed depending upon condition.

I am wondering with the house having uniform joists and flooring how the porch flooring can differ from the house? It would appear that the same joists (basement view) would be running under the front room to the right (if I am visualizing correctly) or at least as far as a center beam.

Caution! I am not an expert so just use my comments to assist your thinking.

Are you referring to the column above the porch, that goes to the porch ceiling?

If the joists that I'm seeing when looking up in the basement are the same joists that are underneath porch, then they appear to be in great condition. Also, those are the same joists that run under the front room to the right.

What do you mean by "how the porch flooring can differ from the house?" I believe it is the same flooring as is throughout the house unless I'm misunderstanding what you mean.

As far as replacement goes, would it be necessary for me to also replace the subfloor (rather than remove it entirely)? I'm wondering if I can get away with just putting down new flooring directly on top of the joists, but then again, this would create a tiny step down from the threshold. Also, would I have to use tongue and groove boards so that water can't run down into the basement? This would mean I can't use composite boards I assume.

 

[AdrianeS]

It's hard to visualize the construction. The porch may have smaller joists on wider centers than the rest of the house as there is no X bracing between joists. If the house doesn't have sub flooring then all hardwood flooring would have to be installed perpendicular to the run of the joists but that could still leave tongue and groove end joints unsupported which seems unlikely. If you have sub flooring then the flooring in all rooms doesn't have to run in the same direction. We're missing something here so don't make any hasty decisions. This may not be a homeowner project.

Ugh, this is not what I want to hear lol! I can't afford to hire someone to do this for me! Although maybe I could pay someone to come and take a look and advise me on what to do.

I just took another closer look at the flooring from the basement ceiling and found something I didn't notice before. You are correct in that the ends of the tongue and groove flooring are not supported by joists as shown in this picture:

The above picture is what's under the front room to the right of the porch (and throughout the rest of the house).

However, the board under the porch itself are different, which I hadn't noticed before:


But these boards to don't appear to be the same subfloor I'm seeing from the top of the porch, once I remove the upper layer of boards, because those boards are rotting, leading me to believe I have 2 layers of subflooring and then the tongue and groove boards on top of those?

 

[AdrianeS]

I found some clues. Hard wood floors nailed directly to joists were 7/8" thick and boards were longer. They were installed perpendicular to joists and more board ends could be seen aligned when looking across the floor. If floors were laid parallel to joists spacers were added between joists at 16' intervals. This was early in the 20th century later hardwood flooring was reduced to 3/8" thickness and installed over sub flooring.

I read where some porch flooring was installed over sub flooring with a layer of tar paper. This Old House made mention of some use of a lead caulk to waterproof tongue and groove joints when over basement or crawl space.. This is my speculation but to achieve the same level for porch and interior floors maybe shallower joists were used to accommodate the extra material.

Interesting! I also read somewhere that roofing material was used for waterproofing. Is it possible that there are the joists that I'm seeing from the basement, which has a layer of wood over them, and could there possibly be another layer of joists above this and directly below the porch floor? I've been searching and searching through porch construction and I just can't seem to find anything that resembles what I have. Everything is just simply the joists with porch flooring directly above. Maybe I'm not using the right search terms. I appreciate your help though!

 

[AdrianeS]

Thanks, I would venture to say that under the subfloor you see from the removed material, you will likely find some form of roofing material, acting as a pan, and if so, I'd be hesitant about removing further, because there are modern materials which may better serve your reconstructing the deck.

How would I go about waterproofing in the current day and age? Depending on the amount of rotting subfloor, I may be able to get away with just replacing a few boards, but unfortunately I won't know the severity without tearing off the whole porch.

On second thought, could a moisture meter detect below the top layer of porch boards?

 

[Eddie_T]

I wasn't clear with my statement. I was thinking about floor level, how could porch and interior floors be the same level if the porch floor has multiple layers sitting on the same joists?

In your pic I see that end joints in flooring between joists are occasional and well supported by adjacent boards. Something I read implied that boards (circa 1920s) might have been six feet long so that could happen. I can't find any reference to 18" centers (only 12, 16 and 24).


Are your joists all the same depth? Don't those under the main portion of the house have some X bracing?


Is there any indication the the portion under the gable is either an add-on or was originally all porch and a portion enclosed to enlarge the LR?

 

[Eddie_T]

A master carpenter friend of mine has a small portico entrance to his home. I think it had wood decking that he later covered with slate. Slate or tile might be an attractive option for your weatherproofing but could present a winter hazard with your lake effect snow. Maybe a mat for traction in the winter could resolve that issue.

I was in Cleveland for a month at NASA LeRC (now NASA GRC) before being assigned to a contractor's facility in MD so I have experienced a bit of your weather. Flying into Hopkins I have at times noticed your area covered with snow but Hopkins and GRC completely clear.

 

[Snoonyb]

How would I go about waterproofing in the current day and age? Depending on the amount of rotting subfloor, I may be able to get away with just replacing a few boards, but unfortunately I won't know the severity without tearing off the whole porch.

On second thought, could a moisture meter detect below the top layer of porch boards?

There are several membrane systems available, some are applied in shower pans and those that roofers use to reinforce pathways on flat roofs for access to roof mounted equipment.

To maintain your present deck height you'll likely need 2X6 T&G with an elastomeric caulk at the intersections and fastened only under a flashing where it intersects the dwelling, and also at the perimeter. The use of deck screws piloted and inserted into the sides, instead of face drilled, will keep them hidden, for aesthetics.

 

[AdrianeS]

No, there is no extra bracing anywhere that I can see in the basement. However, I just noticed that the joists under the porch are different than those under the rest of the house. The joists under the porch run east and west:

While the rest of the joists run north and south:

I do not believe the porch was any kind of addition. It appears to be original to the house but I guess I can't say for certain. Where I live, there a lot of houses identical to mine all with the same type of porch and a front room next to it, so I'm assuming it's original.

 

[AdrianeS]

A master carpenter friend of mine has a small portico entrance to his home. I think it had wood decking that he later covered with slate. Slate or tile might be an attractive option for your weatherproofing but could present a winter hazard with your lake effect snow. Maybe a mat for traction in the winter could resolve that issue.

I was in Cleveland for a month at NASA LeRC (now NASA GRC) before being assigned to a contractor's facility in MD so I have experienced a bit of your weather. Flying into Hopkins I have at times noticed your area covered with snow but Hopkins and GRC completely clear.

Winters can be terrible here! This past winter we didn't see a lot of snow though.

I suppose tile could be an option but first I'd still like to figure out just how my porch was constructed in the first place. How many layers of wood there are and how much is rotting and would need to be replaced. May end up cutting through a small section to figure this out. I was hoping someone might be familiar with how it was built but I can't find anything so far.