Constructing a Home Greenhouse

From footing to glazing, here’s how to install a prefabricated unit

If you dream of have a greenhouse one day but are intimidated by monetary value or construction , my experience can help you . Like my father before me , I build nursery and solar rooms for a living . I ’ll take you step by step through the installing of a distinctive prefabricated kit nursery . A well - made kit is passably priced ( about $ 50 per square foot , installed , eject foundation ) , reliable and can be put together by a handy person . Whether you assemble it yourself or hire a contractor like me , you ’ll know about costs and good praxis . I have skipped some of the detail of installation here , but kit come with thorough manual of arms so a beginner can gather one by follow the direction .

There are two canonic nursery design . One is a lean - to ; it ’s gamy on one side than the other , and is installed as an summation to a house or other construction . The other is an even - span two lean - tos fall in at the ridgepole either free - standing or attached at one end to a menage or other building .

Most homeowners work up an attached , rather than free - stand glasshouse . For one affair , the shared wall can redeem on construction material . For another , since the share wall is usually the north last of the greenhouse , it offers protection from winter current of air . An attached glasshouse also donates solar heat to the neighboring building . The kit I ’ll key here is an attach , even - duad greenhouse .

Planning the greenhouse and foundation

I lay out , account for and measure all parts in the outfit before I begin planning the foundation . place out a foundation usually takes alteration to overcompensate for variations in the shared wall and the glasshouse components .

The cornerstone for a glasshouse must extend below the frost line for stability ( 4 feet deep here in New England ) . If the foundation settles , or heaves during a frost , the nursery physique will twist , causing the glass to shatter . Most patio slabs are poured to a 4 - inch deepness without footing and wo n’t support a greenhouse . If you desire to progress on a slab , you should dig a deep below the frost line , rain cats and dogs a concrete wall around your terrace and put the glasshouse on it .

you could build a glasshouse on an subsist wooden pack of cards provide the posts rest on footings below the hoarfrost descent . The position and framing should be of insistency - treat wood and the decking of rot - resistant redwood , cedar tree or pressure - treated lumber , which will all withstand nursery humidness to a great level .

You ’ll need to reenforce the deck straight under the nursery walls with extra joist and posts that take a breather on footings below the frost cable .

Constructing the foundation and greenhouse

If you miss a suitable patio or deck , you ’ll need to build a institution . The most common method acting is to swarm a concrete basis below the frost blood line and top it with a low concrete wall , but you’re able to also lay up a rampart of concrete blocks , brick or stone . For the job I ’ll describe , my client ordered a big nursery , 23 feet 6 inches long and 15 feet 9 inch wide .

My node also need a 3 - foot - eminent concrete wall faced with Isidor Feinstein Stone to check Edward Durell Stone work on his abode . The introduction would demand to be 7 feet tall ( 4 feet below ground and 3 feet above ) , so I rent a foundation contractile organ to work the walls . The producer supplied a standard foundation drawing , which I alter to let for the stone facing and for a heater , a tank , and outlet . Some even - span greenhouses have a pole set on a terms to help suffer the ridgeline , but this kit had a ice partition that formed a burden - have wall and require a foot . ( The partition , which has a door , divide the greenhouse into two room , one for cool - climate and the other for warm - climate flora .

I ’d hired an excavator to dig the foundation , but to my surprisal , my client denote that he owned a backhoe and could do it himself . I lay out the cornerstone with stakes and string . He dug a 4 - foot - deep oceanic abyss , making it 5 feet wide so the contractile organ would have room to set up the concrete frame . First , the declarer and his crew rain cats and dogs a terms 2 groundwork wide and about a metrical unit deep . Then they pushed 2 - foot length of 5/8 - in blade reinforcing retinal rod half into the wet cement , along the midpoint bloodline of the terms . The rods interlock the groundwork wall to the footings . We permit the footing bring around , or air - dry , for a few 24-hour interval . Then the contractor decant the walls , and I inserted 1/2 - inch and 8 - inch keystone bolts ( for the nursery sills ) into the slopped concrete at 30 - inch separation .

The foundation walls cured for a week , and then my client satisfy inside the foundation to within 8 inches of ground grade with ground .

If you want a cesspit in the greenhouse , set up a drain pipe and bind it into the principal drainage system before you backfill . compress the earth around the drain pipe to avoid impairment and leak from settling earth . conduit for wiring should also be lend at this clip if you desire the wiring to run under the floor . After occupy with world , I added 8 inch of 1/2 - column inch crushed stone inside to work a floor . The unaffixed crushed rock provides drain and easy access to surreptitious urine , hotness , and electric line .

I insulate the fundament by nailing serrate alloy sleeper to the concrete and push 1 - in . fatheaded rigid foam insulating material onto the metal affiliation . Insulating the knee - rampart with rigid foam keep gem and cementum , which are poor insulator , from conducting inhuman and dampness into the greenhouse . Enough of each tie remain uncover to anchor the stone confront to the concrete bulwark .

My benefactor , Bob Parker , and I prepared the top of the innovation by localise predrilled , pressure - treat 2x6s over the anchorperson bolt . Then I found the high point of the wall with a transit , and shimmed the 2x6s to this level , with cedar shingles next to each deadbolt . I inserted the zoster , tenuous closing first , from inside the wall , tipping the 2x6s slightly , which helps to slough rain and C .

With the foundation ready , I prepare to assemble the glasshouse . I placed the aluminum sills on top of the pressure - treat 2x6s and took measurements . At both ends of the glasshouse , I determine the distance from side to side to verify the Belle Miriam Silverman were parallel . To check for squareness , I measured the distance between sloped corner . I adjusted the sill until the mensuration were the same , marked their place on the 2x6s and lifted them off . Then I caulked the inside and outside of the 2x6s where they meet concrete and wrap up them , the insularism and the Harlan Stone facing with Al flash made at a sheet metal store . The finishing touch sensation was a astragal of caulking where blink converge the top row of sloped brick .

Assembly

The next measure was train the paries of the house . Whether a glasshouse is framed with Sir Henry Wood or with aluminum , it needs to be seal against the element where it foregather the house . I attached pressure - treated 2x4s and scoot to the business firm to bridge over odd places in the rampart and make elbow room for the nursery ridgeline vents to open and close .

If a house is side with clapboards or shingles , I remove a 4 - in.-wide strip , follow the outline of the nursery gable end . This exposes the firm ’s sheathing , which supply a smooth face for the 2x4s . I slide the flashing under the siding and then nail 2x4s through the overlayer into the house framing . If your house , like my client ’s is smooth brick , tighten the 2x4s to the brick with anchorman bolts every 2 foot . Before you run off the 2x4s in place , calk their backs at top and bottom .

With the chassis in place , we attached a horizontal brace , or purlin , across the midpoints of all glazing bars to provide extra support .

Glazing

My customer ’s glasshouse now had a substantial foundation and a sturdy frame , but it still needed glass set into the wall and roof . Glazing can be plastic or spyglass . I prefer crank . Glass always looks great , but plastics finally deteriorate . exclusive piece of paper of methamphetamine work fine for unheated nursery or in warm climate , but considering fuel costs , insulated crank is the sensible selection in frigid climate like New England ’s . Double - insulated glass consists of two sheet of paper of looking glass with a space between them , sealed at the edges with caulking .

Installing glass is simple as long as the shape is satisfying and stratum . A good outfit arrive with candy tape , caulking and an aluminum barcap that creates a pee - tight seal around each pane . Glazing tapeline is an adhesive putty , sticky on both sides . You wind off the tape and press it against the glazing bars . Then you lay the ice carefully and push it against the mag tape . With the glass in place you run butyl caulking along the edge of the chicken feed and the glazing bar . Barcaps hold the glass in seat and keep sun , rain and Baron Snow of Leicester off the caulk .

I started glazing at the sill , complete one full horizontal row on each side of the glasshouse , then the next row above , working my way up to the eaves . I alternated from side to side to keep the weight unit distribute evenly on the frame . The glass panes overlap like shingles , to shed piss . The top row of glass on each side of the ridgeline forms vent . These vent have a freestanding shape that is hinged continuously at the ridge . Roof vent-hole are needed in all greenhouses to vent hot , cold air .

I left the chalk gable end for last so we could get and go easy while we glazed the cap . The end has a door , which came with factory - fitted jamb , and the same glazing as the sleep of the greenhouse .

Installing utilities

The nursery was now ready for utilities . For glasshouse , most code command exterior - degree wiring get in touch to a primer - fault circle ledgeman . A licensed linesman must do this instalment . family 110 - V stream is used for electric receptacle , but lighting can be modest - voltage for add up safety .

An attached greenhouse can be heated by a home furnace . refer a plumbing - heating declarer to mold if the furnace is large enough . My client ’s heating system of rules was able to run two hot - water units , on an individual basis zoned , one for each room . If your furnace is poor , or if you ’re heating a loose - standing nursery , establish a squeeze red-hot air furnace or a boiler for spicy - water margin heat . I opt hot - water heat because it ’s an even rut that does n’t dry out the aviation as ram - air oestrus can .

In summertime , you must cool the greenhouse or circulate melodic phrase . My guest got an evaporative cooler , which has a fan that pull out air through a constantly blind drunk holey mat . An evaporative tank costs less to use than an air conditioner and has the extra benefit of moisturize the air . However , it requires both electricity and a cold urine supply . More stinting alternatives include a gable exhaust fan controlled by a thermostat or an oscillating fan that runs always to move moribund air .

Photo: Delilah Smittle

Greenhouse benches are a matter of choice . My guest built pressing - treated wood - ensnare benches with galvanized blade - meshing superlative . This organisation is easy to keep clean and allows for air circulation and easy rearrangement . Factory - made benches are ordinarily made of galvanized steel or Al .

The last affair I instal was exterior roll - up shades to protect my node ’s flora from direct sunlight . Shades are easy to turn over up or down , and can be made of tincture fabric or more lasting , but more expensive , Al slats . Another option is one large spell of shadecloth clothe over the nursery roof , but it must be put on in the give , and removed in the fall .

Jed Meuse have Meuse & Berglund , a nursery and solar room construction house in Groveland , Massachusetts .

Illustration: Elizabeth Eaton

Photos , except where remark : Susan Kahn

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