Detached buildings – buying, selling and maintaining

guide to detached buildings

Buying a house with detached buildings is a great opportunity for additional storage, work, rental or living areas.   Well-maintained detached buildings can add utility and value and with proper repairs and maintenance detached buildings can last as long as the main home.

In this article, we will discuss ideas that can help people buy, sell or maintain homes with detached buildings with greater confidence.   We discuss the 3 most common problems with detached buildings and how to fix them.  We also discuss the best way to install electrical and plumbing in detached buildings.

Examples detached buildings:

  • Offices
  • Garages
  • Barns
  • Tiny homes
  • Studios
  • Mother-in-law cabins
  • Tool sheds, garden sheds, and storage sheds

The 3 most common problems with Detached buildings? 

(and how to fix them)

Problem #3: Neglect

Often, homeowners neglect to take care of their sheds and detached buildings.  Neglect leads to decay, air quality issues, and depreciation.

The Solution:

Regular Maintenance

  • As a general rule, painted surfaces should be re-finished every 7-10 years and stained surfaces should be refinished every 3 years. 
  • Wood structures should be treated for wood-destroying insects as needed (in our area wood buildings should be treated annually for carpenter bees).   
  • Gutters should be cleaned at least twice a year. 
  • For sheds and detached buildings without central heating and cooling it is recommended to have a dehumidifier installed to help control humidity during the rainy, hot, and humid months to prevent moisture and mold/mildew damage- the dehumidifier should be set to around 55%RH and the condensate should be professionally drained to the plumbing or exit to the outside).
  • Shrubs, vines, mulch, storage, and trees should be kept away from the siding to help prevent water damage.

Problem #2: Missing Gutters

Many pre-manufactured storage buildings and detached structures have minimal overhangs– this is unfortunate because a good overhang will protect the siding and trim over the long term.  Most storage buildings do not have a gutter system.  A properly installed and maintained gutter system will protect the siding, trim, and windows/doors from wind-blown rain and decay over the long term.  Gutters also help prevent erosion, settling, and water damage to the foundation.

The Solution:

Gutters are relatively inexpensive and are worth the cost to protect your investment.  Even small sheds and vinyl sheds can benefit from gutters.  Find more information about gutters here.

A good gutter system

The building should have a gutter system with downspouts and extensions that direct water away from the foundation areas.  Ideally, the structure has at least 1′ roof overhangs to help protect the siding/trim from water damage.  Wood siding/trim should be painted every 8 years or as needed. 

Problem #3: Grading issues

The condition that deteriorates detached buildings more than any other is when wood framing is installed too close to the ground- this is especially true for sheds placed on posts, skids, or blocks.  Sheds are very commonly installed over a block or two which is not enough maintenance, inspection, and repair access.  Also when the floor or wall framing of detached buildings is installed near the ground over time mulch, sediment, and other organic debris, mound up against the wood framing of the structure, and the moisture starts a process of decay, wood destroying insects infestations and air quality issues which will eventually cause the structure to be worthless.  With detached buildings, water’s destruction is rapid and total and can usually be observed within a decade or two.

The Solution:

Adequate clearance under floor framing:

There should be a minimum of 2′ clearance between the grade and the bottom of the floor framing- this clearance prevents pre-mature decay and allows a ‘crawl’ area for maintenance, inspections, and repairs.  Most of the issues above can be eliminated with a structure that was built higher off the ground.  Most smaller detached buildings on skids, blocks, or posts can easily be raised or moved with beams, car jacks, and trailers.  In some cases, the grade can be excavated around the perimeter to improve clearance and access.  Another advantage to providing this clearance is there is good access for future electrical, plumbing, or insulation improvements.  Installing a detached building higher off the ground will require a ramp or steps to the door however the extra expense and trouble will yield life-long dividends by preserving the structure.  If the building cannot be moved or raised the surrounding grade should be repaired to direct water away from the building on all sides.  Even when the framing is too close to the ground, grading and drainage repairs can at least extend the life expectancy of the structure.

Solid Posts and Footings

Posts should be installed over concrete footings– ideally, the concrete footings extend below the frost line and at least 8″ above grade- the depth of the frost line varies depending on the region (in the Asheville area the frost line is 16″ below grade).  Pouring permanent concrete footings before the shed is built or even when the shed is raised will help prevent decay and settling over the long term.

Good grading around the building

Grading and drainage should be directed away from the building and especially away from the post footing areas to prevent settling.  

Electricity and Detached Buildings

Electrical service improves the utility of a detached building and provides power for dehumidification or cooling which helps control moisture and extend the life expectancy of the structure.  The service, or Amp capacity, and overall quality of installation may vary greatly– detached buildings may have no power, an extension cord run from the house, or a professionally installed 100 amp panel or larger, and everything in between.  When buying a house with detached buildings the buyer should consider the Amp rating of the sub-panels and overall construction quality.  A good inspector can help anticipate repair/upgrade costs.

A note on the Ampacity or ‘Amp’ rating:

Ampacity refers to the maximum load a system can safely handle.  The ampacity of a sub-panel is typically limited by the thickness of the wires, the rating of the panel, and the distance of the service wires.  These calculations are best performed by a licensed electrician.

Best Practice Electrical Installations for Detached Buildings:
  • Minimum of 60 amp service
  • Breakers, panels and wiring should be properly sized and rated
  • Modern sub-panels require a 4-wire cable — 2 hots, 1 neutral, and 1 ground (rather than 3 wires)
  • Neutral and ground wires should be isolated or not connected to the same bus bar or panel
  • Conduit, or protective tubes, should be used to protect the service wire from damage (below panels and underground).
Common Electrical defects in Detached Buildings:
  • 3-wire service only– recommend driven rod at the detached building for grounding
  • Missing GFCI outlets – generally an easy fix
  • Neutrals and grounds not isolated – generally an easy fix
  • Breakers not compatible with the panel – generally an easy fix
  • Corroded panel due to high humidity – this is unsafe and the panel and breakers should be replaced
  • Missing conduits – selective repairs or a full upgrade may be needed
  • Service line not buried deep enough to prevent possible damage – full upgrade/replacement will be needed
  • Under-sized service wires – full upgrade/replacement will be needed
  • Missing sub-panel – full upgrade/replacement may be needed

Plumbing and Detached Buildings

Most detached buildings don’t have any plumbing.  Some detached buildings will have a utility sink and others will have similar plumbing to small houses.

Best Practice Plumbing Installation for Detached Buildings:
  • Permitted and professionally installed
  • The water service line should be buried below the frost line with 14 gauge trace wire to help with the location
  • 3″ or 4″ Schedule 40 PVC waste lines with adequate slope to septic/sewer
  • Main plumbing vent that exits through the roof
  • Proper traps/vents/air admittance valves at all plumbing fixtures
  • Main shut-off valve and shut-offs for each plumbing fixture
Common Plumbing Defects in Detached Buildings:
  • Un-permitted — check with city/county planning
  • Hose type water service (non-permanent)  – full replacement needed
  • The water service line that is not buried below the frost line and is subject to freezing/bursting – full replacement needed
  • Inadequate heat source to prevent plumbing from freezing – HVAC installation needed
  • The waste line exits to the yard, not the sewer/septic system – full replacement needed
  • The Septic system is not designed to accommodate an additional septic load of the detached building – check with city/county planning
  • Un-professional (DIY) installation of plumbing (missing traps/vents/etc…) – selective repairs or full replacement needed

Detached buildings add utility and value to a home.  Unfortunately, when corners are cut during the installation and maintenance is neglected the life expectancy of the shed will be shortened significantly.  A good home inspector is an invaluable resource for people buying, selling, or maintaining detached buildings to help them assess the condition and anticipate repairs and upgrades.

Asheville Detached Building Inspectors

Builder Buddy is your resource for Detached Building Inspections in the Asheville area.  We also provide Shed Inspections, Mother-in-law inspections, ADU inspections, Studio Inspections, STR or Short Term Rental Inspections, Tiny Home Inspections, Single-wide trailer inspections, Outbuilding Inspections, Barn inspections, Detached garage inspections, Garage inspections, Detached Building Wood Destroying Insect Inspections (“Pest” Inspections) and more.

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