Converting garage to living space questions.

[djmdammit]

Long time lurker here

I have gotten a lot of great ideas and motivation from reading posts on this forum but now that I'm about to convert a portion of my garage to living space I figure its time to actually post something.

I have a 24x30 attached garage with a 16x7 door. I have to borrow some space from the long side of the garage for a new 10x30 sunken den/kids playroom. The 16x7 door will be replaced with a 9x7.

I will probably have a few different question as this DIY project takes shape but the one thing I want to decide up front is how to heat it and how to finish the top course of block.

THe house has baseboard heat so my hope is that I can just expand the loop with copper pipe and slant fin type radiators mounted as low as possible. I will have to run pipe through the wall that divides the garage from the new room but I dont expect that to be an issue. I dont know how to finish the top course since it sticks out though? Molding over drywall over insulation I'm guessing. I have 2x4 walls and a 2x6 mudsill. I hope to upload some pics later.

Has anyone dealt with this before?

 

[D.J.]

Pictures?
Welcome to GJ!
Don't forget to put location in your signature lines.

 

[kenfath]

As a long time lurker trust you realize there are many on this forum that would be willing to make a 'great personal sacrifice' to have a two garage. Your idea is doable as outlined but I keep coming back to WHY would anyone give up a two car garage? Especially when there might be a way to have the best of both. Finish the entire space which would give you a 'great room' that could serve as a den and playroom, a place to entertain a large number of guests, a get-a-way, a workplace and still have parking for two cars. Suggest providing a separate HVAC unit for comfort.

Haven't figured out how to satisfy your idea for anything sunken. However, after seeing the aftermath of my neighbor's flooded living room from a broken water purifier and another friend's fall into a sunken room, I'm inclined to stay away from such.

You may want to check out if any local codes require having a two car garage, as some do. Also check on what is required for permitting, etc. Nothing would be more frustrating to have to tear out an improvement because it wasn't properly permitted when constructed.

 

[Randy in Maine]

Since I built my new garage, I am converting the attached single car garage to sort of living space for my wife to use as a "guest area" and a stained glass workshop. There is always a price to pay.

For me that involves getting the spray foam guy over here to do the sidewalls and ceiling, and having a new 5" thick concete pad poured over the existing floor, and 1" of insulation to allow for the radiant floor heat. I will retain the vaulted ceiling.

I already have the new French doors to replace the 9' x7' garage door and will be installing a new "man door". Washer and dryer, utility sink, and a small propane fired "woodstove" will go out there.

I will find the most uncomfortable futon made to make sure that nobody stays too long.

 

[tylernt]

You may need to raise the floor on the new living space. Codes require the garage to be a certain number of inches lower, so that spilled fluids or heavy gases do not enter the living space.

 

[CNGsaves]

Gotta ask the obvious question . . . . You realize this will likely LOWER the property value of house?? Going from a 2 car garage to 1 car garage is a big market price killer. I would strongly recommend against it. Almost certainty that front fascia of house will have compromised look.

ALTERNATIVE: What about building addition or "L" to house out into the backyard for space you want?? With proper planning, it could have "basement" space for storage or even tornado shelter.

Personal Experience: Current older house I bought has "sunken" living room which really was the old 2 car garage. It's very nicely done with brick fireplace and brick on front of house with big plate-glass window so not noticeable from curb view (no driveway or anything left). Lot is pretty large so a detached 24' x 34' garage was built on other side of house with new driveway. False floor put into sunken living room so drop is only 10" but that room is ALWAYS cold (thus I'm skeptical that prior owner insulated properly . . . AND . . it's on N end of house). Also getting proper forced air heat/AC is difficult.

Good luck as no easy or cheap solutions.

 

[djmdammit]

As a long time lurker trust you realize there are many on this forum that would be willing to make a 'great personal sacrifice' to have a two garage. Your idea is doable as outlined but I keep coming back to WHY would anyone give up a two car garage? Especially when there might be a way to have the best of both. Finish the entire space which would give you a 'great room' that could serve as a den and playroom, a place to entertain a large number of guests, a get-a-way, a workplace and still have parking for two cars. Suggest providing a separate HVAC unit for comfort.

Haven't figured out how to satisfy your idea for anything sunken. However, after seeing the aftermath of my neighbor's flooded living room from a broken water purifier and another friend's fall into a sunken room, I'm inclined to stay away from such.

You may want to check out if any local codes require having a two car garage, as some do. Also check on what is required for permitting, etc. Nothing would be more frustrating to have to tear out an improvement because it wasn't properly permitted when constructed.

We've been using the garage as an extension of the house for a couple of years now, but we need more permanent living space, at least until we move onto a bigger house. I have a 2-yr old and twins on the way.

 

[djmdammit]

You may need to raise the floor on the new living space. Codes require the garage to be a certain number of inches lower, so that spilled fluids or heavy gases do not enter the living space.

good point. I know the floor will be 3 inches higher but that may not be enough.

 

[djmdammit]

Gotta ask the obvious question . . . . You realize this will likely LOWER the property value of house?? Going from a 2 car garage to 1 car garage is a big market price killer. I would strongly recommend against it. Almost certainty that front fascia of house will have compromised look.

ALTERNATIVE: What about building addition or "L" to house out into the backyard for space you want?? With proper planning, it could have "basement" space for storage or even tornado shelter.

Personal Experience: Current older house I bought has "sunken" living room which really was the old 2 car garage. It's very nicely done with brick fireplace and brick on front of house with big plate-glass window so not noticeable from curb view (no driveway or anything left). Lot is pretty large so a detached 24' x 34' garage was built on other side of house with new driveway. False floor put into sunken living room so drop is only 10" but that room is ALWAYS cold (thus I'm skeptical that prior owner insulated properly . . . AND . . it's on N end of house). Also getting proper forced air heat/AC is difficult.

Good luck as no easy or cheap solutions.

You bring up excellent points. I've been very careful to not make alterations that would lower the value of my home. In my market this conversion will still keep me ahead of the game as most homes of similar size/price do not have a garage, or they converted their one car to permanent living space. My house is on the small side and the garage is huge relative to the house so the two extremes will even out nicely when its done. When I built it I had to obtain a property variance as my lot is on the small side, and also on a corner which gives it weird setback numbers. I'm already maxed out.

I totally agree with you on the appearence of a converted garage. That's a big pet peeve of mine. I dont know what I can do about that aside from cutting out the concrete and turning it into a mulch bed.

 

[DPelletier]

as far as your heating issue goes; I'm sure your existing hydronic system wasn't sized with the capacity to add the additional 300 square feet. That being the case, baseboard electric heat would be the cheapest and easiest solution by far.

Dave

 

[Mike007]

as far as your heating issue goes; I'm sure your existing hydronic system wasn't sized with the capacity to add the additional 300 square feet. That being the case, baseboard electric heat would be the cheapest and easiest solution by far.

Dave

As as HVAC contractor in NJ, without even seeing his system, I can say with 99.9% certainty the boiler will have the needed capacity and then some. I rarely, rarely see heating systems particularly boilers that aren't oversized by 200% or more. I don't know why. My own home has 30,000 BTU's worth the baseboard, which is correct. For some reason a few years before I bought the home someone installed a 105,0000 BTU boiler. It really makes no sense.

 

[tylernt]

I rarely, rarely see heating systems particularly boilers that aren't oversized by 200% or more. I don't know why.

Say a house was built decades ago with minimal insulation and poor airsealing, so they really needed 100K BTUs. Later, the house was insulated to modern standards / upgraded to modern windows.

Now it's time to replace the boiler. Homeowners don't want to pay extra for a Manual J calculation, so to stay competitive, HVAC contractors don't push them (mine didn't even mention it when I had him install a new furnace). The contractor knows he'll get callbacks for an undersized system, so he either keeps the same BTU rating as the old unit when sizing the new unit, or does a quick guesstimate and deliberately oversizes the new furnace to make sure the customer never calls back to complain about not having enough heat.

Not intended to slam HVAC contractors... cheapskate homeowners are the issue. And I'll happily include myself in the cheapskate category, since I didn't pay for a Manual J myself. I did do my own heat loss calculation before I called my HVAC contractor, though -- I estimated a 60K BTU would be the bare minimum and my contractor chose to install an 80K, which was the same size as the old furnace. Hey, better to be a little too big than a little too small, right?

 

[djmdammit]

As as HVAC contractor in NJ, without even seeing his system, I can say with 99.9% certainty the boiler will have the needed capacity and then some. I rarely, rarely see heating systems particularly boilers that aren't oversized by 200% or more. I don't know why. My own home has 30,000 BTU's worth the baseboard, which is correct. For some reason a few years before I bought the home someone installed a 105,0000 BTU boiler. It really makes no sense.

How do you measure BTUs worth of baseboard? I'd be interested in taking whatever number I come up with and comparing it to my boiler output.

 

[Dan Babb]

What if you build a wall that will allow you to keep the garage door as is. Then you have some storage in front of the new wall. It would make the change less permanent and allow a future owner to easily convert back if the want the garage space.

Build the front wall with a drop space for the tracks that allows the door to open all the way. If properly trimmed, it wont look bad when you open up the garage door. Use that wall for hanging stuff so your other car spot isnt cluttered with ****.

 

[tylernt]

Dan Babb, that's genius.

 

[djmdammit]

I considered that too but it would ruin my plan to open up the the living room into the new room. Kinda tough to explain without pictures I guess. Plus I couldn't put a window in the front of the room if the door were there.

 

[Mike007]

How do you measure BTUs worth of baseboard? I'd be interested in taking whatever number I come up with and comparing it to my boiler output.

Common 3/4" baseboard is rated at rough 600 BTU's per foot with 180* supply water.

 

[Mike007]

My experience tells me an accurate manual J (Ive run thousands of them) will oversize by 25% or more which is fine. It's probably built into the program as a safety factor. Then your contractor added another 20,000 BTU's on top of it. In theory, your furnace could be almost 2X larger in capacity then need. This becomes a critical issue if the ductwork was designed around an older furnace with less efficiency, a much heavier heat exchanger, and the ability to operate normally with high discharge air temps. For me as a contractor, the smaller the furnace the better. It cost the customer less up front, will use less fuel, make the customer more comfortable and be less likely to run hot due to airflow issues. Obviously I have no idea if this is the case with your home or not.

Say a house was built decades ago with minimal insulation and poor airsealing, so they really needed 100K BTUs. Later, the house was insulated to modern standards / upgraded to modern windows.

Now it's time to replace the boiler. Homeowners don't want to pay extra for a Manual J calculation, so to stay competitive, HVAC contractors don't push them (mine didn't even mention it when I had him install a new furnace). The contractor knows he'll get callbacks for an undersized system, so he either keeps the same BTU rating as the old unit when sizing the new unit, or does a quick guesstimate and deliberately oversizes the new furnace to make sure the customer never calls back to complain about not having enough heat.

Not intended to slam HVAC contractors... cheapskate homeowners are the issue. And I'll happily include myself in the cheapskate category, since I didn't pay for a Manual J myself. I did do my own heat loss calculation before I called my HVAC contractor, though -- I estimated a 60K BTU would be the bare minimum and my contractor chose to install an 80K, which was the same size as the old furnace. Hey, better to be a little too big than a little too small, right?

 

[djmdammit]

Common 3/4" baseboard is rated at rough 600 BTU's per foot with 180* supply water.

Thanks for this. Very helpful. I have about 40,000 BTUs worth of baseboard and a 80,000 BTU boiler.

 

[pseudorealityx]

How do you measure BTUs worth of baseboard? I'd be interested in taking whatever number I come up with and comparing it to my boiler output.

GPM * 500 * (water Temp IN - water Temp OUT)

 

[Mike007]

Thanks for this. Very helpful. I have about 40,000 BTUs worth of baseboard and a 80,000 BTU boiler.

See, I told you it would be enough.